Spinoza and Tuberculosis: His Disease and Devotion

[Tuberculosis can be a difficult disease to diagnosis. The following is working under the assumption that the diagnosis of "phthisis" for Spinoza's long-running pulminary problems is best understood as the disease tuberculosis.]

The Influence of Disease

It is interesting that of all the influential facts we seem to have about Spinoza’s life, his tuberculosis may be neglected only as much as his lens-grinding has been. Very little of how debilitating this disease can be, nor its chronic nature seems to be considered when framing a picture of Spinoza’s motivations for life decisions. At most his tuberculosis, called in biographies “phthisis”, its name derived from Greek, gives us a remote picture of a man made weak and coughing at times. Then there is the oft repeated, but unsupported, yet romantically satisfying thought that he died not only of his TB, but also from inhalations of glass dust from his lens-grinding. Yet the facts of the disease seldom seem to enter into the explanations for Spinoza’s decisions and life turns.

Spinoza’s early biographer Colerus tells us that Spinoza had been suffering from tuberculosis for more than 20 years when Spinoza died at the age of 44, in Feburary of 1677:

Spinosa was a Man of a very weak Constitution, unhealthy and lean,
and had been troubled with a Pthysick above twenty years, which
oblig’d him to keep a strict course of Dyet, and to be extreamly sober
in his Meat and Drink. Nevertheless, his Landlord, and the people of
the House did not believe that he was so near his end, even a little
while before he died, and they had not the least thought of it.

If we track backwards, this would place the first bout with tuberculosis very close to the date of his father’s death (March 28, 1654), and his taking over of the family firm (September 1654). Spinoza’s step mother, Esther, died only five months before his father did (October 14, 1653), after a year of serious illness, itself a year after Spinoza’s own sister Miriam had died. Tuberculosis is a highly contagious disease when symptomatic, (when living 24 hrs a day exposed for two months you have a 50% chance of being infected).

To more fully picture the condition, the symptoms of active tuberculosis include:

- A cough which may last three or more weeks and may produce discolored or bloody sputum
- Unintended weight loss
- Fatigue
- Slight fever
- Night sweats
- Chills
- Loss of appetite
- Pain with breathing or coughing (pleurisy)

That Spinoza may have contracted tuberculosis from his father, and may himself have become symptomatic in the year 1656 or so is not something that many people have considered. (To his credit, Nadler does momentarily bring up the idea that Spinoza may have suffered from the same thing that killed his step-mother, 155; why his step-mother and not his father I do not know.) These are years that we have very little historical record of, and a struggle with the illness may very well be a reason for this (the highest risk for deveoloping of the disease is in the first two years after infection). When Spinoza applied for orphan status in March of ‘56 (two years after his father died), and when the cherem is read against him in July of the same year, removing him from the community, having failed to pay the family firm’s imposta tax, he may indeed already have been tubercular, and perhaps even seriously so. This would make his excommunication something of quarantine, not only of ideas, but also in a vividness of metaphor, of body and illness. But we really need not go that far, though it should be considered. We have had such a variety of motivations projected onto Spinoza at this time, from Jonathan Israel’s thought that Spinoza was at this time attempting to be excommunicated by being outrageous, simply to climb out from the burden of onerous debts, to Wim Klever’s notion that Spinoza at this point was so invested in his political and spiritual education with Van den Enden, long broken from the community, the excommunication was but a triffle. Either of these may be so, but if Spinoza had by now become symptomatic, his illness certainly would have played into his inability to run the firm to profit, or more significantly, his desire no longer to conduct that vigorous business.

Chekhov’s Example

Tuberculosis does not always head in a straight line, by my understanding. It can be recurrent. Chekov, for instance, who like Spinoza also suffered from the disease over a twenty-year period, as an original onset had an intial bout of fevers in December of 1883, and then three days of coughing up blood a year later in December of 1884. It was not until six years later, from the strain of trans-Siberian travel, that again the disease seemed to surface, much more forcefully. Chekhov, like Spinoza, died in his 44th year, at the peak of his intellectual and creative powers. [Citing "Chekhov's Chronic Tuberculosis" (1963), by Brian R. Clarke]. This is how one medical information website describes the nature of its chronic mechanism:

In addition, TB can spread to other parts of the body. The body’s immune (defense) system, however, can fight off the infection and stop the bacteria from spreading. The immune system does so ultimately by forming scar tissue around the TB bacteria and isolating it from the rest of the body. Tuberculosis that occurs after initial exposure to the bacteria is often referred to as primary TB. If the body is able to form scar tissue (fibrosis) around the TB bacteria, then the infection is contained in an inactive state. Such an individual typically has no symptoms and cannot spread TB to other people. The scar tissue and lymph nodes may eventually harden, like stone, due to the process of calcification of the scars (deposition of calcium from the bloodstream in the scar tissue). These scars often appear on x-rays and imaging studies like round marbles and are referred to as a granuloma. If these scars do not show any evidence of calcium on x-ray, they can be difficult to distinguish from cancer.

Sometimes, however, the body’s immune system becomes weakened, and the TB bacteria break through the scar tissue and can cause active disease, referred to as reactivation tuberculosis or secondary TB. For example, the immune system can be weakened by old age, the development of another infection or a cancer, or certain medications such as cortisone, anticancer drugs, or certain medications used to treat arthritis or inflammatory bowel disease. The breakthrough of bacteria can result in a recurrence of the pneumonia and a spread of TB to other locations in the body. The kidneys, bone, and lining of the brain and spinal cord (meninges) are the most common sites affected by the spread of TB beyond the lungs.

“experience had taught me”

At the very least, if Spinoza was showing symptoms of the disease as early as 1656, as Colerus’ very rough estimate would place them, Spinoza’s life decisions to not pursue wealth, but rather a life of philosophy, must be cast in a slightly different psychological light. Spinoza writes of his change of mind in The Emendation of the Intellect:

After experience had taught me that all the usual surroundings of social life are vain and futile; seeing that none of the objects of my fears contained in themselves anything either good or bad, except in so far as the mind is affected by them, I finally resolved to inquire whether there might be some real good having power to communicate itself, which would affect the mind singly, to the exclusion of all else; whether, in fact, there might be anything of which the discovery and attainment would enable me to enjoy continuous, supreme, and unending happiness.

I say “I finally resolved,” for at first sight it seemed unwise willingly to lose hold on what was sure for the sake of something then uncertain. I could see the benefits which are acquired through fame and riches, and that I should be obliged to abandon the quest of such objects, if I seriously devoted myself to the search for something different and new. I perceived that if true happiness chanced to be placed in the former I should necessarily miss it; while if, on the other hand, it were not so placed, and I gave them my whole attention, I should equally fail(Elwes translation).

This is thought to have been Spinoza’s earliest philosophical text, before the Short Treatise, Shirley placing its composition between the years 1657 and 1660. What, we may ask, was this “experience” that has taught Spinoza the futility of social life, the uncertainty of “fame and riches”. Are these generic experiences that all would have, perhaps even the particularities of watching his father die in tubercular fashion, after a life of substantial monetary and honorific gain? Or, more jarringly, was it the onset of the same disease, the same coughing up of blood, that he had seen his father and his step-mother succumb to? This would certainly have a life-turning effect.

We see no evidence for debilitation in April of ‘55 in the record of Spinoza’s subpoena and physical confrontation with the Alvares brothers. He is struck so hard his hat comes off, something which might afford a reference to physical weakness, but none is mentioned. In fact, from the vague description it seems that only the hat seems worse for wear. And in ‘58, from Fra Tomás’ 1659 report to the Spanish Inquisition, we find Spinoza to have a handsome face “de buena cara” with light, clear, but perhaps pale skin, “blanco”. This would seem to put him in good health. The only thing I may mention is that there is great contrast given between his very dark hair and eyes, and the paleness of his skin. Prado, in whose company Spinoza is in, has a “brownish” complexion on the other hand. While he may have been in good health at the time, the paleness of his skin may have been due to some convalescence. In 1659 he is described by another informant for the Inquisition as having a “well-formed body, thin, long black hair, a small moustache of the same color, a beautiful face”.

But as we have seen from the example of Chekhov, an attack of tuberculosis does not nessarily leave one debilitated for life. The body’s immune system can indeed isolate the infection, and return one to health, even robust health, only to be susceptible to the disease later, and times of great stress or weakness. Assuming that his disease was that of tuberculosis, one cannot conclude that Spinoza’s health was never robust, as some have thought.

The Beginnings of “Isolation” and a Conserve of Roses

A great deal of investigative imagination and analysis has gone into the question as to why Spinoza left Amsterdam for the much more quiet Rijnsburg in 1661. Gullan-Whur suspects that something had frightened Spinoza in a way that the excommunication had not, perhaps something to do with the Spanish Inquisition. Perhaps an increasing pressure from Dutch authorities and Jewish reaction made it unsafe for Spinoza to continue his Amsterdam life, some feel. And there is the account of a knife attack outside the theatre, if it is to be believed. Or it is assumed that he went to Rijnsburg to be closer to the Collegiant movement. Spinoza’s very good, generous friend Jarig Jelles bought a large new house on the Herengracht in Amsterdam in 1660, but Spinoza did not move in. First he moved to near Ouderkerk, and then to Rijnsburg near Leiden’s university. Why? We are told his move towards isolation was so that he could be away from distractions from friends, so that he could concentrate on his work, and this is no doubt true. But is it too much to notice that his withdrawl from friends and the air of the city may have been really a question of health? Was it not that tuberculosis struck him again, and it is was in full view of his mortality, and even questions of contagiousness, that brought him to concentrated isolation.

By September 1661 he writes to Oldenburg that his Short Treatise, (one may say is most overtly spiritual work) is still a work in progress. There is no hint of his illness in their correspondence. In the winter of ‘62/’63 he has the company of Johannes Caesarius, who is living with him, helping him in a none-too-satisfactory fashion with the geometrical treatment of Descartes’ philosophy. Gullan-Whur reads Caesarius to be Jan Casier, a student of Van den Enden’s school, now a young, Dutch Reformed ordinand (1642-77). As a note of perhaps significant coincidence during this period, Adriaan Koerbagh, Spinoza’s friend and comrade in spirit of the same age, had received his doctor of medicine from nearby Leiden University in 1659, with a dissertation on the causes of Tuberculosis, Disputio medica unauguralis de Phthisi. In 1661 he became a Doctor of Law, also at Leiden, and in Koerbagh’s later trial he admits that he had discussed philosophical matters with Spinoza numerous times in the years 1661-63. Having conducted a study of the causes of tuberculosis, one wonders if Koerbagh had ever seen Spinoza as a patient, or if Adriaan himself had tuberculosis which weakened him (as he would died only within a few months of being sentenced to prison and hard labor in 1669). Along this line of argument, a conserve of roses is the only conserve mentioned in the Bloemhof  (1668). The suppressed Bloemhof  was a 672 page dictionary of terms written by Adriaan and his brother, meant to demystify the use of foreign phrases and technical jargon, putting into the vernacular the verbal obfuscations by which eclesiastical, medical and legal “experts” carried out much of its authority over the common man. In 1665 it is for a conserve of roses that Spinoza says he is waiting (Letter 28), writing to the physician Johan Bouwmeester who was an intimate of Adriaan Koerbagh. Spinoza had visited his friends in Amsterdam earilier in the year, and during his visit to the city he seems to have suffered a recurrence of his tuberculosis:

At the same time I also expected some of the conserve of roses which you promised, although now for a long time felt better. On leaving there, I opened a vein once, but the fever did not abate (although I was somewhat more active even before the bloodletting because of the change of air, I think). But I suffered two or three times with tertian fever, though by good diet I have at last rid myself of it and sent it packing. Where it went I know not, but I don’t want it back.

By this time Spinoza has moved from Rijnsburg to Voorborg near The Hague, and he distinctly associates the “air” of Amsterdam with the onset of his illness. It would appear likely that this causal belief was consistent in his life, and thus part of his reason for moving out of Amsterdam in the first place.

Voorburg, Not So Quiet

At this point I would like to take up some of the psychological criticism aimed at Spinoza by his biographer Gullan-Whur. In making her assessment of a certain flaw in Spinoza’s self-perception she provides us with a rather telling description of the house Spinoza moved into in Voorburg. She points out that although Spinoza, in her opinon, plays the role of the isolated sage, being crankily troubled by intrusions, he moved into one of the most bustling, connected locations in all of Voorburg: Voorburg was a rural village, but Benedictus had not choosen to live in a peaceful part of it, for the Kerkstraat houses, huddled on a terrace and generally having only a gable loft above their ground floors, were flanked by the market place and a boat-servicing harbour beside the Vliet. Yet, whole this lodging was feverishly cacophonous compared with sleepy Katwijkerlaan, he never complained…nothing was easier that getting to any Dutch city from Voorburg. The philosopher could leave home almost at the ringing of the horse-boy’s bell to catch the trekschuit. Voorburg being on the way to everywhere (the canal system joined the River Schie at Delft, and continued south to Rotterdam and Dordrecht), he should have foreseen a continuous flow of callers (154-155).

She goes onto conclude that Spinoza himself does not own up to his own emotional needs for company, caught up in the production of his own image. I might suggest that Gullan-Whur has severely misread Spinoza’s contradictory needs for isolation and for contact. This essentially the mindset of the chronically, if sporatically, ill. Rather than this being a profound conflict of conscience, the inability for Spinoza to understand his own needs, Spinoza’s tuberculosis and his philosophical/scientific endeavours, required both isolation and contact. Indeed I would suggest that it was likely the disease that forced Spinoza to reconsider his life, and it was this ever-present relationship to his own body and mortality that made his rationalist philosophy most concerned with the freedoms of the body. Gullan-Whur’s example of reading the man is actually instructive for all interpretations which ignore his physical histories. In fact all of Spinoza’s metaphysical positions on the body should really be seen in the light of his continual threat of tuberculosis. 

It is persuasive to infer, and least as persuasive as any other reasoning I have encountered, that Spinoza’s father and step-mother indeed died of tuberculosis, and that Spinoza had contracted the illness from them. On average, people have a 50 % chance of becoming infected with tuberculosis if they are in close contact eight hours a day for six months. If Colerus’s estimate is right that Spinoza had struggled with the disease for more than twenty years, this would put his first attack right at the decisive years of the late 50s, as Spinoza was forming his new political and theological relationships with Van den Enden and Prado, leaving behind the family business. (By stating this length as more than 20 years, Colerus at the very least seems to want to place the illness before Spinoza’s milestone move from Amsterdam.) This encounter with a disease that may have killed his father and step-mother surely would have shaped the decisions Spinoza was making. And the resultant dedication to philosophy, science and selective isolation should not be considered outside of this persistent awareness of both his disease and the effects it may have had on others. All the complexities of influence that we can convincingly conjure up may very well pale to the experience of the fatal fever and cough a year after you watched your father and step-mother, and perhaps even sister, pass under similar conditions. It is agreed that this is a time of plagues, and the death of family members and close friends, certainly by 1664 was not uncommon. This does not mitigate the personal effect the disease would have had upon Spinoza in the determinative years of 1655-1658, not to mention the consequences of managing the disease over a lifetime.

Why the timing and substance of the disease has not been well considered by biographers and interpreters of Spinoza’s life, I do not know quite understand, except for the recognizeable need to comprehend the man in terms of much vaster, more abstract historical and intellectual factors.

The Magnification of Bidloo’s “Spinoza” Microscope

Embryonated egg capsule of Fasciola hepatica.

 

The Magnification of the Proposed Spinoza Microscope

If, and I have to stress if, we can establish that Govert Bidloo used a microscope made by Spinoza in his study of the parasite F. hepatica, and if we can establish that he viewed the eggs of the organism, individually, then we might be able say something about the magnification of Spinoza’s glass. There are several factors involved, but here I hope to make an educated guess at the quality of the glass Spinoza may have produced.

There are two primary factors involved in assessing the capacities of a 17th century microscope, that of magnification and that of the clarity or resolution of the glass (other factors that effect observation are specimen preparation and specimen lighting). A very powerful magnification might produce dramatic proximity, but without clarity, much of the detail might be lost. Such is the case that a microscope of much lower magnification may produce observational results far superior to those brought on by another, stronger microscope.

We find this in the comparisons between surviving single and compound microscopes. Brian Ford in his Single Lens: The True Story of the Single Microscope cites a 1930 survey of P. H. van Cittert of Ultrecht, which looked at the type of microscopes available between 1700 and 1830. Van Cittert concluded that most biological observations (plant and animal cells, blood cells and cell nuclei, (estimates not below the 6-8 μm range), could be accomplished with single-lensed magnifications of not much more than 100x, while comparable observations using compound microscopes would have needed a magnification of 250x. The conclusion being that compound microscopes of the era were inferior to their simple lensed counterparts (129).

The resolution of the single-lensed scopes simply was better. These are scopes were made with a very small glass-bead lens, with very short focal lengths that pushed the instrument right up against what was being viewed, nearly so to touch. But, one could not simply make a tiny ball, spun from a melted thread of glass, and achieve optimal results. Van Leeuwenhoek, who was expert at this, learned to grind and polish his lenses so that they achieved a remarkable clarity. Reports of those who have looked through his lenses are always of the striking clarity he was able to achieve (not their magnification), like nothing they had seen before. This would give his lenses, which were already quite powerful in terms of magnification, an added advantage of clarity, making them the best in Europe.

Microscopium Praestantissimum

It is within this context that one has to read the compliments paid to Spinoza’s microscope lenses. His microscope is called “microscopium praestantissimum”, most excellent, by Kerckring, in his Spicilegium anatomica (1670). And Spinoza is praised by Bidloo. These are two knowledgeable men in the study of anatomy, mostly familiar witha variety of other instruments. I would suggest that it is not the magnification that each is thinking of, but rather of the clarity of the image, the focus of detail that his instruments provide. This was a time when glass itself was of quite an impure quality, and any improvement in the luminosity of image was likely preferred even over the gains brought about through magnification alone.

To support this supposition, we have the telling compliment paid by the none-to-generous Christiaan Huygens in a letter to his brother Constantijn, in the year 1667 from Paris:

“the [lenses] that the Jew of Voorburghas in his microscopes have an admirable polish”, and then a month later, “the Jew of Voorburg finishes [achevoit] his little lenses by means of the instrument and this renders them very excellent”.

We can see that Spinoza possesses a technique which brings about the much sought after polish that goes beyond the abstractions of mathematical refraction. His lenses are small (but we cannot tell if they are part of compound or simple microscopes). At this point Van Leeuwenhoek’s coming observations, nor his microscopes, are not known to the scientific community, so Spinoza’s polished lenses may have stood out all the more. 

The next question to consider is the level of magnification that would be required to view the what Bidloo reports to van Leeuwenhoek in 1698. These are the eggs of the parasite F. hepatica. These are approximentlyin size 70 x 130 μm (by one report I have read, and by email correspondence with professor Don Duszynski of the University of New Mexico). These are well within the range of 5 - 8 μm of P. H. van Cittert 1930 survey for single lens microscopes at a bit more than 100x magnification. And given the compliments paid to the polish of Spinoza’s lenses, we might assume perhaps a better than average resolution for his instruments.

If we expand our question in the direction of magnification, we find that Van Leeuwenhoek was able to achieve at the very least, a magnification of 266x. Brian Ford sums:

Leewenhoek’s best surviving lens provides x266, and it has been claimed that his highest magnification may have been x500. That may be over-optimistic, but it is equally unlikely that one of nine surviving instruments out of a total production of several hundred is going to be the most powerful of them all…The most powerful single lens I have ever seen was produced by a British lens-grinder and approached x1000 (though its resolution was no better than a lens magnifying half as much) and a lens magnifying nearly x500 was identified in a collection of early 19th century mircoscopes in Holland some years ago as we shall see (128).

Edward Ruestow writes much more enthusiastically of the possibility of a 500x lens, suggesting that they certainly would not have been “unusual”, citing a hypothetical design by Hartsoeker of a 770x lens (14). But all this magnification does fall to the question of resolution. Brian Ford finds 500x lenses over-optimistic, Ruestow common. It seems though that all that was needed to see even bacteria withclarity was a finely polished single-bead lens and a well prepared, well-lit specimen. We have as evidence for this Brian Ford’s experiment of observation through Van Leeuwenhoek’s lens, capturing thorough detail of structures less than 1 μm wide.  

a section of cork seen under van Leeuwenhoek's most powerful surviving microscope (266x). The structures are less than 1 micrometer wide.

Alvaro Amaro de Azevedo, who has investigated Van Leeuwenhoek’s possible techniques [ The Challenge Of Grinding Lenses For Single Lens Microscopes ], and has produced a 1000x lens through the simple methods (though with some modern advantages), actually came to realize that in terms of observation capacity, the polishing of the lens was perhaps the most important factor. And he came to conclude that Van Leeuwenhoek would have been able to see most bacteria with a 150x lens (as he himself has). This is what he told me:

Through the lenses and microscopes I have done, I could see several types of bacteria, including cocci, spirillum and bacilli. I make my microscopes using basically the same concept Leeuwenhoek used just trying to see what he could have seen and I´m totally convinced that he has seen these microorganisms with no greater magnification than 150 X. The main issue here is the polishing quality he was able to achieve as with an ordinary polishing one would not be able to see a fraction what can be seen with a perfectly polished lens. It took me three years to find a satisfactory polishing technique to obtain this kind of quality (email correspondence).

Given de Azevedo’s experience and estimate, the example from Van Leeuwenhoek’s existing lens, and the compliments paid to Spinoza’s and “microscopium” and his “vergrootglas”, it would seem safe to assume that Spinoza’s glass used by Bidloo fell withing the 150x range. A compound microscope may have required a greater magnification, a single lens, less. 

I will have to wait until I confirm the context of Bidloo’s use of a Spinoza microscope…I hope to go to the Yale library Monday; then I will hopefully read his egg descriptions, perhaps see illustrations, and may uncover further information about the details he would have seen been able to observe.  

There are a few things to think about on a wider scale when considering how this impacts our view of Spinoza as both a craftsman and a philosopher. It is known that Spinoza favored smaller lenses than some of his contemporaries for microscopes (Huygens). While great strides were made in the mathematical descriptions of refraction of telescopes (which Spinoza also made), the way that light behaved in the microscope appears to be much less understood or even analyzed. By embracing the smaller of lenses he aimed for greater magnification and shorter focal lengths, but not through the sacrifice of polished clarity. He owned a book on Venetian glass making, and thus was interested in the quality of glass. And the attention he paid to the clarity of the images, not satisfied with just blurred magnification, resulted in a notable polish of the material, suggesting a pursuit of crafted achievement. Bead lenses could be produced at a very fast rate, many in an hour, if one was not discerning. As I have said before, we do not know if he made compound or simple microscopes, there is evidence for both. It strikes me that Spinoza’s concern for polish and clarity, his lasting engagment with the material, is indicative of a particularly embodied connection to the process. And, it was this connection to the material, I believe, that may have distinguished his metaphysics, psychology and political theory from other Rationalists of his age.

Davidson, Spinoza, Aristotle: Veridicality and Organs

A ruminating thought floats behind these considerations.

Is there a connection between a). Davidson’s world thought to be the cause of our beliefs which assumes an inherent verdicality of belief, making of a triangulating community of language users a kind of organ of truth, b). Spinoza’s (proposed) expectation that interactions with his Ethics, that would cause increases in our power to act along a vector of Joy, the proofs of which serving as organs of mental perception, within a cohering affectively bonded sociability, c). and Aristotle’s functional defintion of the products our sense organs as incorrigable.

Further, aside from any imposed normativity, projected upon funcationality, such and organ bound communication of veridicality would open the question up along biological valences of affect and power. Organs can open up to an analysis of the Body Without Organs. Communicated action across functionality.

Gaukroger:

Secondly, perception of special sensibles is incorrigible for Aristotle because it is constitive of the very notion of veridicality. Vision under optimal conditions is the only criterion we posses by which to judge whether something has a particular colour: for example to view something under optimal conditions is to meet all the relevant conditions by which colour is determined. On this account, to distinguish between something really being red, and just looking red to someone with excellent eyesight who views the object under optimal lighting conditions, would simply make no sense…This is not an epistemological account of perception, in the sense of an account that tells of how the veridicality of our knowledge of the natural world can be secured…it is not just that the proper use of our sense organs automatically gaurentees the verdicality of what we perceive, but rather that, given their proper use (i.e. the proper use of normal sense organs operating under optimal conditions) the question of our being mistaken simply makes no sense (159-160).

- Intellectual Biography 159 - 160)

Aristotle, De Anima Book II Part VI (418):

In dealing with each of the senses we shall have first to speak of the objects which are perceptible by each. The term ‘object of sense’ covers three kinds of objects, two kinds of which are, in our language, directly perceptible, while the remaining one is only incidentally perceptible. Of the first two kinds one (a) consists of what is perceptible by a single sense, the other (b) of what is perceptible by any and all of the senses. I call by the name of special object of this or that sense that which cannot be perceived by any other sense than that one and in respect of which no error is possible; in this sense colour is the special object of sight, sound of hearing, flavour of taste. Touch, indeed, discriminates more than one set of different qualities. Each sense has one kind of object which it discerns, and never errs in reporting that what is before it is colour or sound (though it may err as to what it is that is coloured or where that is, or what it is that is sounding or where that is.) Such objects are what we propose to call the special objects of this or that sense.

Spinoza’s Eyes of the Mind and the Grinding Form

Three References to Sight

Still, we sense and experience ourselves to be eternal. For the mind no less senses those things that through thinking it grasps, than those it has through memory. For the mind’s eyes, by which it sees and observes things, are demonstrations themselves…

Ethics, 5P23s

We must investigate, I say, whether there is any other affirmation or negation in the Mind except that which the idea involves, insofar as it is an idea…so that our thought does not fall into pictures. For by ideas I understand, not the images that are formed at the back of the eye (and if you like, at the middle of the brain), but concepts of Thought [or the objective Being of a thing, insofar as it exists only in Thought]Ethics, 2p48s.

…after I have come to know the nature of vision and realise that it has the property of making us see one and the same thing as smaller at a distance than if we were able to see it near at hand, we infer that the sun is bigger than it appears.

The Emendation of the Intellect

To follow up on yesterday’s thinking, these are the three substantial references to mental vision in Spinoza which one must come to terms with if we are to understand the effect the grinding of lenses and the making of optical instruments had upon his thinking. Spinoza speaks very little about light, in terms of an explanatory metaphor, and when it takes up the idea of vision, it is in very selective ways.

Considering the first two quotations above, we see his firm resistance to any “picturing” of truths, something he relegates solely to the experiences of the imagination. Thinking, or having a truth thought, is not to be understood in any sense of having a picture of the world (and he distances himself either from Descartes, or popular conceptions of Descartes in this passage). But when considering the second of these, see still understand that the Mind, expressed in the succession of ideas of which it is composed, actually senses. We sense, and the Mind senses (both sentio ). But if we follow the pairs, “we” sense and experience, although the mind “senses and observes”, giving clue to the shift Spinoza is thinking of. In our collective sensing, we passively experience the world, but in our intellection, we observe the world. (Yet part of the process of intellection, as Spinoza conceives of it, is the realization that we are not distinct from it.)

I am still caught by the notion that the demonstrations or proofs of propositions are literally the eyes of the mind (remember the apodictic connecton between logical demonstration, and a craftsman’s demonstration: what “showing” means). I recall a study that I read on Plotnius, and the author was talking about how or why we read philosophers of the past. He suggested that as one submits themselves to their architecture of arguments a subtle, perceptual shift happens. The world, our very perceptual experience of it, alters. This is how Spinoza conceives of his propositions and proofs operating. They are not so much seen as indefatigable statements that secure a fact, (although most certainly he conceives of them as correct and true), they are meant much more as a interaction, a pedagogy, which alters one’s experiences of the world, promoting intuitions which will grant greater freedom and greater capacity to act. They are cybernetic combinations. I have used that world before, but intentionally so, because Spinoza defines a body as a communication of parts. For Spinoza, I believe, the parts of the Ethics, combine in a useful way with the parts of our Body-Mind, to produce an interaction, a communication, which empowers the person, in assemblage. In a sense, the conatus that gave rise to the Ethics, the conatus that preserves the Ethics in print and discussion, combines with the conatus that preserves the reader, to produce One, collective, meditative, thinking and acting body. The material dimension of this must be understood.

If one is to draw from the lens-grinding analogy, a lens is ostensibly made by grinding a glass-blank in one’s free hand, against a metal (copper or iron) form or lap, which holds the curvature that is desired. The off-hand either drives the spinning of the lathe so that it spins something like a potter’s wheel. (Or this can be accomplished with a foot petal, leaving the off-hand free.) As one drives the metal dish in concentric revolutions, it clearly manifests a changing, yet fixed state, turning but stable. Against this metal form, upon which abrasives of various grits are poured, the glass is pressed, until it gathers the shape desired. The fineness of the grits and processes of polish are made in stages.

This is something how I imagine Spinoza’s Ethics was to work. The first armature of arguments for Substance, and then continuations on to knowledge and power, are meant to grind down the rough edges. This is where the greatest resistance comes I believe in many readers. The propositions seem to lack application, and may appear to indulge in terminology that grates. Yet, the work progresses to grades of increasing finesse, until the human emotional condition is addressed, and then the glass is given a subtle polish, in hopes of increasing its speed and capacity.

The propositions and the proofs exist to be ground upon. One tests one’s mind against them, pushing against their rigid character, and their tight cross-reference. It is not so much that one proposition is right, and convincing, but rather that their very atomic, veined fabric is meant to be engaged in, as one presses against its spinning form. The hardness of the material and its ideational webbing wears away the rough edges of the mind, and suddenly you are seeing something, however mutely, or blurred. This is how I imagine that Spinoza thought of his text, and why he used the geometrical method for his master work. He was not thinking to convince, but rather to engage, to cause the mind to “sense and observe” in a different manner.

How Platonic this may sound, the meeting of a Form to rough material, but the dynamic, material character of the form itself denies any transcendence. The interaction is seen as an aid, but also as a combination. Here the third quotation from the top of the page comes into view. By acquiring knowledge about the nature of vision, we come to see differently. We come to see the sun as further away, such that we can act more freely in regards to it. We sense and observe in a continuity. The propositions and proofs that we have pressed ourselves against have polished us, not because there is perfect vision, but because there is better vision, a vision that is understood as material.

If we compare this “mind’s eyes” notion to Descartes’ “mind’s eye”, from which it likely drew influence, we detect a radical difference:

Rule Nine: We must concentrate our mind’s eye totally upon the most insignificant and easiest of matters, and dwell on them long enough to acquire the habit of intuiting the truth distinctly and clearly.

The Regulae

Like Spinoza, Descartes wants to promote an intuition, the capacity to see clearly with great immediacy. Yet Descartes imagines a mental vision that is closely focused on what is before one. Whether this be a small, causal relation, or an indubitable fact, Descartes wishes to build surety upon surety. Spinoza though wants mental vision to be comprehensive and vast. Any close comprehension moves very quickly to a totality of perceptions, from which all else gains clarity. The over-arching Coherence is that from which individual distinction and merit comes from. And it is for this reason that his optical conceptions were based on the notion that vision requires a wide-view clarity of focus, refining both the center and the borders. And it was for this reason that he composed his Ethics vastly, not so that he could cover every base, but so engagement with it would produce a symmetrical, whirling, grinding curvature of the mind, one that could focus all events, as best as possible, yet ever with a view to the expresssion of the body, as a body. And part of this final understanding is that not only are we formed by the things we are ground against, in the frictions of our living, but we are ever in communication with them. And I suspect Spinoza wants to say, in telling us that demonstrations (of every kind) are the eyes of the mind, that because of this, our organs of “sight” extend far beyond us, into the infinity of affects and motions that communicate themselves to us, each along a tensioned, discerning line of power.

Spinoza’s Ethics, A Polished Lens

Polishing Lenses and Propositions

I want to set out some basic thoughts on a guiding intuition of my research on Spinoza’s optical experiences and products. This is the notion that perhaps Spinoza conceived of his Ethics, and the entire network of cross-referenced, mutually inferring propositions, demonstrations and scholia, to be something like a lens, polished to the improvement of our mind; and by virtue of his metaphysical parallelism, to the improvement of our body, giving those who use it, greater capacity to act. The analogy that is at work here is a hopefully satisfying and sophisticated elaboration of “he polishes lenses, he polishes propositions”, a thought given birth in Borges’ poem on the philosopher.

If we are to embrace this analogy in a literal sense so as to gain access to the ways Spinoza’s lens-grinding may have affected his approach to his metaphysics, drawing a conceptual connection between the attentive, precise, manual craftsmanship he engaged in during the day, and that studious argumentation he produced at night: the idea of the “eyes of the mind” is one that we should be take careful note of. 

I shall not treat the more philosophically suggestive of his uses from the second part of the Ethics here, where he warns against what he seemed to find as a Cartesian temptation, to “fall into pictures”:

We must investigate, I say, whether there is any other affirmation or negation in the Mind except that which the idea involves, insofar as it is an idea…so that our thought does not fall into pictures. For by ideas I understand, not the images that are formed at the back of the eye (and if you like, at the middle of the brain), but concepts of Thought [or the objective Being of a thing, insofar as it exists only in Thought]

Ethics, 2p48s.

This is a passage that is important, and deserves a separate treatment, though I have approached it elsewhere, (not sufficiently) :A Diversity of Sight: Descartes vs. Spinoza , Spinoza: The Body of Ideas as Lens . Here though I want to instead look at Spinoza’s use of the phrase in the Fifth Part, where he addresses the problematic claim that through the mind we know that we are eternal. I do not want to focus at all the subject of the eternity of mind, but rather his use of the phrase, and his way of illuminating what he means by it. I quote the passage below, with two of its most successful translations, along with my own:

At nihilominus sentimus experimurque, nos aeternos esse. Nam mens non minus res illas sentit, quas intelligendo concipit, quam quas in memoria habet. Mentis enim oculi, quibus res videt observatque, sunt ipsae demonstrationes…

Ethics V P23s

Still, we sense and experience ourselves to be eternal. For the mind no less senses those things that through thinking it grasps, than those it has through memory. For the mind’s eyes, by which it sees and observes things, are demonstrations themselves…(Mine)

…still, we feel and know by experience we are eternal. For the Mind feels those things that it conceives in understanding no less than those it has in memory. For the eyes of the mind, which sees and observes things, are the demonstrations themselves…(Curley)

Nevertheless, we feel and experience that we are eternal. For the mind senses those things that it conceives by its understanding just as much as those which it has in its memory. Logical proofs are the eyes of the mind, whereby it sees and observes things…(Shirley)

We can see what appears to be an analogy, the mind’s eyes are demonstrations, or as some translate, logical proofs. I think it is important to understand that because of Spinoza’s parallelism (again, the principle that anything that occurs mentally, in the exact same order and connection occurs in extension), we have to consider anything, including thoughts and arguments, along with their material counterparts. Understanding that the demonstrations and proofs of the Ethics are not just ideas, but also, as text are also material expressions of Substance, our relationship to them is not just that of a mind to an idea, but also our body to the body, a material assemblage. If we are to think consistently along with Spinoza, the mind’s eyes literally become the demonstrations of the Ethics, such that our minds and body come into material and ideational combination with their reality. In this understanding, we literally “see through” the text of the Ethics. It is not just prosthetic, but cybernetic to our capacity to act, giving us greater freedom, as a body.

Spinoza via Wittgenstein?

This passage from Spinoza was highlighted by Wim Klever in his essay “Anti-Falsificationism: Spinoza’s Theory of Experience and Experiments” found in Spinoza: Issues and Directions : the Proceedings of the Chicago Spinoza Conference(1986). There he puts it into relation to two Wittgenstein citations, which help make clear the way in which we can “see through” proofs or demonstrations:

“Because of the proof our view will be changed… Our view will be remodeled… The proof guides our experiences, so to speak, in distinct canals [ in bestimmte Kanäle ].” - Remarks on the Foundations of Mathematics III (30-31).

“In another mind-space - one might say - the Thing [ das Ding ] appears differently.” Remarks on the Philosophy of Psychology (98).

There is an experiential sensing with the mind, an actual perception, in the process of thinking, and argumental proofs not only are means by which the mind senses, their material existence are the organs of the mind, as we combine with them. And if we follow Wittgenstein’s lead, through our thinking [Spinoza's  intelligendo ] we sense res, things and situations. The proofs and propositions of the Ethics can be considered as material combinations which enhance our powers of action, through their conditioning of our experiences.

As I have pointed out elsewhere, Deciphering Spinoza’s Optical Letters , Descartes, in his Dioptrics, conceived of the telescope as a literal extension of the physical extension of the eye. His hyperbolic model of the ideal lens was meant to accomplish the same refractions that normally occur at the surface of the eye, just further out, so that “…there will be no more refraction at the entrance of that eye” (120) (as he says of his prototype, water-filled model of a telescope). And, as I have pointed out in the same article, because Spinoza wants to understand seeing as a “mind’s eye” event, Spinoza’s ideal lens was a more panoptical design, one that focused rays equally, comprehensively, coming from all directions: based on the powers of the sphere.

I suggest that Spinoza’s Ethics, in its symmetrically of internal reference, was thought by Spinoza to be something of a physical-mental extension of the mind, a rationally polished refraction of all the kinds of causal relations a human being could undergo, meant to bring those events into rough focus so that in that clarity, we may have a greater power to act. Just as Descartes’ imagined his hyperbolic telescope to be attuned to the narrow focus of a frontally discerning Will, extending the eye out into space, so Spinoza, more grandly, pictured the Ethics literally to be the eyes of the mind, propositions and demonstrations being panoptical perfections, to the degree that humanly we, or he, could make them. These “eyes” were vectors of power.

Spinoza's letter 39 diagram, with Descartes' hyperbola projected upon it, to show the contrast in ideal visions

This has been a rough outline of the general idea I am putting forth, founded on the essential Spinozist assurance that whatever occurs mentally, occurs physically, and Spinoza’s pan-directional ambitions in his thinking of optics.

Govert Bidloo, A Spinoza Microscopist?

Physician to the King and Another Spinoza Microscope?

[The arguments below I present prospectively, waiting for a confirmation of the source]

I stumbled upon some evidence that there is a second Spinoza microscope in the historical record, and it is my hope that this glass may bring to view more of the details for which I have been straining. Thus far, the only first hand report we have is from Spinoza’s fellow Latin student, and possible van den Enden disciple, Theodore Kerckring, who in his Spicilegium anatomicum  (1670), describes how with Spinoza’s glass he had seen a “infinitely minute animalcules” teeming upon the viscera. This description is to be questioned, firstly, because Kerckring himself warns us a few sentences before, that all observations of microscopes have to be doubted; but also because Kerckring reported elsewhere some microscopic observations which plainly come from the imposition of fantasy upon sight.

In this case the account may be more sobering and exact, though I have yet been able to actually assess the content of the claim. The report comes apparently from Govert Bidloo, and man of fairly high standing, and apparently connections to Spinozist political movements of his day. In 1694 Bidloo was appointed professor of anatomy and medicine at the university of Leiden, a post to which he was not able to well-attend due to also becoming the personal physician to stadholder William III, who would die in his arms in 1702. If indeed Govert Bidloo did use and favor a Spinoza microscope, he was a well-connected anatomist and physician, and public champion of microscopic investigation.

Collaboration with van Leeuwenhoek: Parasitic Protozoon

The fact of Bidloo’s use of a Spinoza microscope is at this point circumspect, as for the moment I have only a summary of the mention of praise for a Spinoza microscope-glass (vergrootglass), in a memoir-letter written to the famed microscopist Antony van Leeuwenhoek, subsequently published in the same year, 1698. I do not read Dutch, so I had to rely upon the summation of a website owner to understand its content.

“Passage from a letter of Govard Bidloo (Henrik van Kroonevelt Ed., 1698, page 27) a memoir to Antonie van Leeuwenhoek, about the animals which are sometimes found in the liver of sheep, on the etiology of diseases (the Plague) and referring to remarks of scientists abroad on his work, and quoting the quality of the Magnifying glass made by Benedict de Spinoza.”

This is found here. The citation given, aside from the letter itself, is not traceable. Perhaps it is a television production: [52] “Cells of Spinoza”: Tetsuro Onuma, Representative of Yone Production Co.Ltd. (2002).

The phase “quoting the quality of the Magnifying glass” I assume probably means “citing the quality”. Because the context is missing for me, there is no way to affirm what I would suspect, that Bidloo is writing to van Leeuwenhoek about his observations of small parasites and their eggs, as found in the liver of sheep, and it is by virtue of the excellence of Spinoza’s glass that his observations are assured. This is somewhat also how Kerckring references his Spinoza microscope.

Historical Context For Bidloo’s Letter to Van Leeuwenhoek 

Two decades before Bidloo presented his findings to van Leeuwenhoek, in 1674 van Leeuwenhoek was startling the world as he peeled away the curtain of the microscopic, revealing to a new level of exact description and illustration, a world of minute animals and structures. Under his tiny, spherical lenses the first bacteria and protozoans were coming to life, and he began letting the world know about in through letters written to leading scientists in London. And in October ‘74, he wrote to the Royal Society about his discoveries of “globules” and “corpuscles” in the bile of domesticated animals, the first Sporozoa and parasitic protozoon. It would be as an expansion upon these observations that Bidloo would conduct his own microscopic examnations. I quote here from Dobell’s excellent book in van Leeuwenhoek to give a sense of the early material and Bidloo’s connection to it, first from the letter, and then from Dobell’s commentary:

…in the bile of suckling lambs there are very little globules, and some, though very few, bright particles. which are a bit bigger; besides irregular particles, of divers figures, and also composed of globules clumped together.

The bile of yearling sheep I find to be like that of suckling lambs, only with this difference, that in this bile there are also oval corpuscles of the bigness and figure of those I remarked in ox-bile. (Letter 7 to the Royal Society, October 19th 1674).

I think there can be no doubt that the “oval corpuscles” - called eijronde deeltgensin the original - which Leeuwenhoek discovered in the gall-bladder of one of his “three old rabbits,” were the oocysts of the coccidian Eimeria stiedae; while the comparable structures which he found in the bile of sheep and oxen were, equally certainly, the eggs of trematodes [Dobbell notes: Fasciola hepatica- the worm itself -was well known to L.; for the Dutch anatomist Bidloo (1649-1713) dedicated a little memoir to him, in 1698, in which it was described and figured. If my interpretations be correct, the foregoing extract records the first observations ever made upon the Sporozoa or upon any parasitic protozoon (200)

Antony van Leeuwenhoek and his 'Little Animals'

Eggs and the Source of Disease

It is regarding these Fasiola hepatica that Bidloo is writing to van Leeuwenhoek in 1698, apparently part of a collaboration of observations between the two microscopists. This is how Frank Egerton sums up the correspondence in his article for the Bulletin for the Ecological Society of America : 

Leeuwenhoek examined flatworms (flukes) from the livers of diseased sheep under a microscope and suspected that the sheep got the worms from drinking rainwater that collected in fields (21 February 1679, Leeuwenhoek 1939-1999, II:417-419). He pursued the subject no further until 1698, when he and Professor of Medicine Goderfridus Govard Bidloo (1649-1713) of Leiden University (van der Pas 1978) discussed liver flukes in sheep. Boththen wrote up their observations for publication, with Leeuwenhoek sending his to the Royal Society and Bidloo sending his to Leeuwenhoek, who had them published in Delft. Bidloo sent with his letter an overly precise drawing of a fluke, which shows two eyes, a heart, a circulatory system, and intestines that existed only in his imagination. Nevertheless, Bidloo did recognize the eggs and concluded correctly that the species is hermaphroditic. He also generalized from his observations that these worms seem to cause disease in sheep and that worms probably also cause disease in humans (Bidloo 1698, 1972). Leeuwenhoek went out and attempted to find fluke eggs in fields and ditches, where they might have been deposited in sheep feces (2 January 1700, 1939-1999, ?), but he had no way to identify them if he had found them. The fluke life cycle is so complex that it was not fully understood until the mid-1800s (Reinhard 1957). (53)

"A History of the Ecological Sciences, Part 19"

Indeed, the lifecycle of F. hepatica is quite complex, as it relies upon a symbiont aquatic snail, something no microscope would reveal to these men, but it is good to note that Bidloo's microscope and analysis did properly identify the eggs of F. hepatica, something which may give clue to the magnification of his glass. It would appear that the two men were operating under at least remotely similar powers of glass, and at this point van Leeuwenhoek had achieved magnification really beyond compare for the century.  

Bidloo's illustration of the flatworm F. hepatica

The size of the eggs in question may be in order. They come in the thousands, so together are visible to the naked eye, but the eggs themselves are microscopic, measuring approximately 130-160 µm, or 130/1000th of a millimeter:

According to their optical appearance and approximate measurements, we isolated about 1,300-1,500 ‘large’ eggs from a fairly large quantity of sheep faeces. Of these, 300 were measured and their average size was found to be 154 (143-180) x84 (75-102) µm. Fasciola eggs of normal size found in the faeces of the same sheep measured 129 (107-162)x 71 (61-79) µm.

“Unusually Large Eggs of a Fasciola hepatica Strain” (1982) D. Duwel

As I have not read Bidloo’s account, I as yet cannot tell if his glass resolved such detail, but van Leeuwenhoek’s description of “oval corpuscles” must have. And we should keep our mind open to this possibilities.

If we are to speculate, having identified what Bidloo saw and concluded, and assumed that he used a Spinoza made glass, what was the nature of Spinoza’s “vergrootglas”? Literally, this word means “magnifying glass”, something distinct from the word for microscope. It is the same word used to describe the instruments sold from Spinoza’s estate at auction on November 4th, 1677. (It is even conceivable that this was one of those instruments.) A vergrootglas could be anything from a swivel-armed spectacle glass used for dissection and study, to the very powerful simple, single-lens microscopes that Swammerdam and van Leeuwenhoek used. Aside from the more famous Leiden anatomists who used a simple microscope, we are told that Bidloo’s successor to the university position, Boerhaave, used a lens as small as a grain of sand (Ruestow 95). But the story is unclear. Bidloo was a student and friend to Ruysch, a fellow student and associate of Kerckring from ‘61 onwards, who used magnification quite sparingly, and would have had no need of such an intense and difficult lens.

Devils and Parasites

There is another interesting point of about Bidloo’s biography which makes his 1698 reference to Spinoza’s lens more than a point of curiosity. It is twenty-one years after Spinoza’s death, but something more than simply the persistence of the efficacy of Spinoza’ instrument forces his name into consciousness. Bidloo, the physician of William III, was apparently a political activist of a sort, a champion of republican values. And just the year before his rather vociferousfriend Eric Walden had died in prison, perhaps by suicide following a series of failed suits for his freedom, under the general accusation of being a Spinozist-atheist. Walten’s escalating pamphleted attacks against the Dutch Reformed Church, in defense of Bathasar Berkker’s “The World Bewitch’d”, were fierce and reminiscent of Spinoza’s friend Koerbagh, who also died as a political prisoner. Berkker had maddened the religious in his Cartesian-like argument that because their could be not causal interaction between Spirit and Matter, devils and angels could have no effect on this world. This denial of both the miraculous and the diabolical enraged the pious, and when Walten wrote on Berkker’s behalf, the ire came to be directed towards him, eventually with legal consequence. This connection between Bidloo and Walten I find, thinly, but indicatively here:   

In 1688 he took up the cause of William III against James II and showed himself to be a staunch defender of popular sovereignty and the elective nature of monarchy. Next, he turned to the question of the civil rights of governments over the church, and two local disputes, one concerning the privileges of the regents of Amsterdam, and other Rotterdam tax upheavals. [note, after "regents of Amsterdam": It is unclear which pamphlets in this particular row were written by Walten and which by his friends Govert Bidloo and Romeijn de Hooghe, the famous engraver. See Knuttle, "Ericus Walten", p. 359-383.] (44)

“Eric Walten (1663-1697): An Early Enlightenment Radical In the Dutch Republic”, by Wiep van Bunge, in Disguised and Overt Spinozism In and Around 1770

Whether Govert Bidloo used Spinoza’s microscope in his observations on the hepatica or not, I cannot say for certain now, but his reference in the published memoir, in the context of his observations on parasites of the body and a suspicion that they lead to human illness no doubt reflected to some degree the events that of the years previous, and the sourness of the death of Walten in prison. What comes to mind is Spinoza’s reflection to Oldenburg so many years before, that we are like a worm in the blood, how our perceptions are only most often local to what jostles us, itself a reflection on Kircher’s microscopic discovery of worms in the blood of plague victims. (Some thoughts here:  A Worm in Cheese ). One must remember that this was not only a time of political and religious upheaval, but also a time of plague. The clearness of Spinoza’s glass no doubt, in the minds of his admirers, expressed the clarity with which the political body must be examined. Bidloo’s study of the bile of sheep, in search of parasites with Spinoza’s glass either in hand or in mind, surely struck him as fitting.

Simple or Compound: Spinoza’s Microscopes

Smaller Objective Lenses Produce Finer Representations

A very suggestive clue to the kinds of microscopes Spinoza may have produced is Christiaan Huygens’ admission to his brother Constantijn in a May 11 1667 letter that Spinoza was right in one regard, that smaller objective lenses do produce finer images. This has been cited by Wim Klever to be a sign of Huygens making a concession to Spinoza in a fairly substantial question of lensed magnification:

After some disagreement he had to confess in the end that Spinoza was right: “It is true that experience confirms what is said by Spinoza, namely that the small objectives in the microscope represent the objects much finer than the large ones” [OC4, 140, May 11, 1668]

Cambridge Companion to Spinoza, Wim Klever, “Spinoza’s Life and Works” (33)

And this is how I have read the citation as well, not having access to the original context. But some questions arise. Does this admission allow us to conclude that Spinoza was specifically making compounded microscopes, the kind that Huygens favored? Or are “objective” lenses to be understood to be lenses both of single and compound microscopes. What makes this interesting is that if we accept the easiest path, and assume that Huygens is talking about compound microscopes, then there may be some evidence that clouds our understanding of what Huygens would mean.

Edward Ruestow tells us that be believes that Christiaan Huygens in his 1654 beginnings already had experience constructing microscopes using the smallest lenses possible. If so, Spinoza’s claim regarding compound microscopes would not be new to him (or his brother). Ruestow puts the Huygens account in the context of the larger question of the powers of small objective lenses:

It was not obvious in the early seventeenth century that the smaller the lens - or more precisely, the smaller the radius of its surface curvature - the greater its power of magnification, but smaller and more sharply curved lenses were soon being ground as microscope objectives, at first apparently because, with their shorter focal lengths, they allowed the instrument to be brought closer to the object being observed. The curvature of a small cherry ascribed by Peirsec to the objective of Drebbel’s microscope was already a considerable departure from a spectacle lens…

Whatever the intial reason for resorting to smaller objective lenses, however, it was not such as to produce a continuing effort to reduce their size still further. (A lens, after all, could come too close to the object for convenience.) In 1654 a youthful Christiaan Huygens, already making his own first microscopes or preparing to do so, appears to have ordered a lens as sharply curved as a local lens maker could grind it, and it may indeed have been a planoconvex objective lens with which he worked that year whose curvature, with a radius of roughly 8mm, was still to that of Drebbel’s (i.e. to the curvature one might ascribe to a small cherry). Fourteen years later, however, Christiaan was inclined to lenses with a focal distance of roughly an inch, and he pointedly rejected small lenses as objectives - primarily it seems, because of their shallow depth of focus…In 1680 members of the Royal Society were admiring a biconvex lens no more than one-twentieth of an inch in diameter, and Christiaan Huygens, now with a very altered outlook, would write that the perfection of the compound microscope (of two lenses) was to be sought in the smallness of its objective lens. He claimed at the end of his life that the magnification such instruments could achieve was limited only by how small those lenses could be made and used [note: On the other hand, he also recognized that there was an absolute limit for the size of any aperture, beyond which the image become confused.] (13)

[Ruestow footnotes that the 1654 microscope described as constructed by Christiaan above, is thought by J. van Zuylen is rather the Drebbel microscope purchased by Christiaan's father, Constantijn Sr.]

The Microscope in the Dutch Republic, Edward G. Ruestow

Not only is Huygens’s turn around described, no doubt fueled by his own famed success with the single lens, simple microscope, just after Spinoza’s death, but also Ruestow suggests that Huygens indeed already knew what Spinoza’s claimed, that smaller objectives indeed do make larger magnifications, his objection being not that the magnification is inferior, but simply that the depth of field makes observation problematic. It is unclear if Ruestow’s reading of the 1654 for is correct, so we cannot say for certain that Huygens had this experience with smaller objectives, but it is interesting that Ruestow cites the same year as his concession to Spinoza, (1668, “fourteen years later” without direct citation), as the year when Huygens makes clear what his objection to smaller objectives is. This raises the question: Is the “confession” in context part of an admission of the obvious between Christiaan and his brother, something of the order, “As Spinoza says objectives represent objects with greater detail, but the depth of field is awful? (Again, because I do not have the text I cannot check this.) 

Or, does Ruestow make a mistake? Is it not letters written 14 years, but only 11 years later, when Huygens in his debate with Johannes Hudde seems to have readily accepted the possibility of greater magnification, but makes his preference in terms of depth of field. As Marian Fournier sums: 

Hudde discussed the merits of these lense with Huygens [OC5, April 5, 10 and 17 1665: 308-9, 318, 330-1], who declined their use. He particularly deplored their very limited lack of depth of field. He found it inconvenient that with such a small lens one could not see the upper and underside of an object, a hair for instance, at the same time. The compound microscope had, because of the much smaller magnification, greater defintion so that the objects were visible in their entirety and therefore the compound instrument was more expedient in Huygens’ view (579) 

“Huygens’ Design of the Simple Microscope”

It is important that Hudde is not only championing smaller objectives, he is attempting to persuade Huygens that the very small bead-lenses of simple microscopes are best. Hudde had this technique of microscopy from as early as 1663, perhaps as early as 1657, and he taught it to Swammerdam. In the context of these letters, apparently written just as Huygens and Spinoza are getting to know each other in Voorburg, Huygens’ 1668 brotherly admission reads either as a distinct point in regards to compound microscopes, or signifies a larger concession in terms of his debate with Hudde. There are some indications that Hudde and Spinoza would have known each other in 1661, as they both figure as highly influential to Leiden Cartesians in Borch’s Diary. And Spinoza was a maker of microscopes, as Hudde was an enthusiast of the instrument even then. It makes good that there would have been some cross-pollination in the thinking of both instrument maker’s techniques in those days, but of this we cannot be sure. 

Against the notion that Spinoza has argued for simple microscope smaller objectives with Huygens is perhaps the compound microscopes achieved by the Italian Divini. Divini, in following Kepler’s Dioptice, realizes a compound microscope whose ever descreasing size of the objective increases its magnification. I believe that there is good evidence that Spinoza was a close reader of Kepler’s (see my interpretation of Spinoza’s optical letters: Deciphering Spinoza’s Optical Letters ). If Spinoza was making compound lenses, and he had argued with Huygens that the smaller the objective the better, it seems that it would have been the kind of microscope described below, following the reasoning of Kepler, which he would have made. 

First, Silvio Bedini sets out the principle of Divini’s construction: 

Divini was an optical instrument-maker who established himself in Rome in about 1646 and eventually achieved note as a maker of lenses and telescopes. In a work on optics published in Bologna in 1660 by Conte Carlo Antonio Manzini, the author describes a microscope which Divini had constructed in 1648, based on Proposition 37 of the Dioptrice of Johann Kepler. This was a compound instrument which utilized a convex lens for both the eye-piece and as the objective was reduced so were the magnification and the perfection of the instrument increased (386).

Then he typifies a class of microscope of which Divini was known to have constructed with this line of analysis:

One form consisted of a combination of four tubes, made of cardboard covered with paper. Each tube was slightly larger than the previous one, and slid over the former. An external collar at the lower end of each tube served as a stop to the next tube. The ocular lens was enclosed in a metal or wooden diaphragm attached to the uppermost end of the largest tube. The object-lens was likewise enclosed in a wooden or metal cell and attached to the bottom of the lowermost or smallest tube. The rims of the external collars were marked with the digits I, II, and III, in either Roman or Arabic digits, which served as keys to the magnification of the various lengths as noted on each of the tubes. The lowermost of the tubes slid within the metal socket ring of the support and served as an adjustment between the object-lens and the object. The instrument was supported on a tripod made of wood or metal. It consisted of a socket-ring to which three flat feet were attached (384).

 And lastly he presents an example of this type, which he calls Type A:

(Pictured left, a 1668 microscope attributed to Divini):The socket-ring and feet are flat and made of tin, and the cardboard body tubes are covered with grey paper, with the digits 1, 2, and 3 inscribed on the collar tubes. The lowermost tube slides with the socket-ring for adjustment of the distance between the object-lens attached to the nose-piece in a metal cell, and the object. The ocular lens is enclosed in a metal holder at the upper end of the body tube. It consists of two plano-convex lenses with the convex surfaces in contact. The original instrument had a magnification of 41 to 143 diameters. The instrument measured 16 1/2 inches in height when fully extended and the diameter of the largest body tube was 1 1/2 inches. A replica of this instrument, accurate in every detail, was made by John Mayall, Jr., of London in 1888 (385-386).

“Seventeenth Century Italian Compound Microscopes” Silvio A. Bedini

 This 16 1/2 inch compound microscope indeed may not have been the type that Huygens’ comment allows us to conclude that Spinoza built, but it does follow a Keplerian reasoning which employed the plano-convex lenses that Spinoza favored in telescopes, one that imposed the imparitive of smaller and smaller objective lenses. It is more my suspicion that Spinoza had in mind simple microscopes, but we cannot rule out the compound scope, or even that he was thinking about both.

Futher, Spinoza’s favor of spherical lenses and his ideal notion that such spheres provide a peripheral focus of rays (found in letters 39 and 49), seems to be in keeping with the extreme refraction in smaller objectives in microscopes, although he attributes this advantage to telescopes. More than in telescopes, the spherical advantage in conglobed, simple lensed microscopes, would seem to make much less of the prominent question of spherical aberration. But in the case of either compounds or simples, the increase curvature, and minuteness of the object lens would fit more closely with Spinoza’s arguments about magnification, and Descartes’ failure to treat it in terms other than the distance of the crossing of rays.

Huygen’s Criticism of Descartes’ La Dioptrique

In order to understand Spinoza’s dissatisfaction with and objection to Descartes’ La Dioptrique  (found in letters 39 and 40 linked below), one has to understand the opinions of those contemporary to Spinoza. Below I post a selection from Fokko Jan Dijksterhuis comprehensive book on Christian Huygens, who is well-noted for having been Spinoza’s neighbor in Voorburg.  

La Dioptrique was written, Descartes said in the opening discourse, for the benefit of craftsmen who would have to grind and apply his elliptic and hyperbolic lenses. Therefore the mathematical content was kept to a minimum. Apparently this implied that Descartes need not elaborate a theory of the dioptrical properties of lenses. Descartes adopted the term Kepler had coined for the mathematical study of lenses. He had not, however, adopted the spirit of Kepler’s study. Dioptrice and La Dioptrique approached the telescope from opposite directions. Kepler had discussed actual telescopes and drudged on properties of lenses that did not fit mathematics so neatly. Descartes prescribed what the telescope should be according to mathematical theory. The telescope, having been invented and thus far cultivated by experience and fortune, could not reach a state of perfection by explaining its difficulties. Huygens was harsh in his judgement of La Dioptrique. In 1693, he wrote:

“Monsieur Descartes did not know what would be the effect of his hyperbolic telescopes, and assumed incomparably more about it than he should have. He did not understand sufficiently the theory of dioptrics, as his poor build-up demonstration of the telescope reveals” (OC10 402-403)

We can say that Descartes, according the Huygens, had failed to develop a theory of the telescope. He had ignored the questions that really mattered according the Huygens: an exact theory of the dioptrical properties of lenses and their configurations. La Dioptrique glanced over the telescope that existed only in ideal world of mathematics (37).

Lenses and Waves: Christiaan Huygens and the Mathematical Science of Optics in the Seventeenth Century, Fokko Jan Dijksterhuis

Here we get a sense of Spinoza’s complaint that Descartes may have avoided certain questions due to mathematical complexity, and that Descartes is not dealing with actual telescopes. It is significant to follow that indeed the analogical form of arguments in the La Dioptrique was designed to be in favor of the craftsmen and artisans who were meant to grind Descartes’ miraculous hyperbolic lens, while in life (and theory), it was the great tension with this human and technical reality that that produced the Cartesian telescope failure.

A line by line interpretation of Spinoza’s Optical letters: Deciphering Spinoza’s Optical Letters

Jerry Rothman’s website dedicated to Kepler’s Dioptrice: here

 

A 1940 Review of Theodore Kerckring’s “Spicilegium Anatomicum”

Spinoza’s Microscopist

I post here a link to a 1940 Canadian Medical Association Journal review of Theodore Kerckring’s “Spicilegium Anatomicum”, a work which contains specific reference to observations made with a Spinoza made microscope. Kerckring was a fellow student of Spinoza’s at van den Enden’s Latin school, and then studied anatomy at the University of Leiden when Spinoza was nearby at Rijnsburg, and was likely part of a Cartesian circle which both J. Hudde and Spinoza held some influence over. Wim Klever argues that he was a loyal follower of van den Enden, who he takes also to be Spinoza’s major philosophical influence. Kercking would marry van den Enden’s daughter.

       

click:THEODORE KERCKRING AND HIS “SPICILEGIUM ANATOMICUM” (1670)

by Albert G. Nicholls

To give context, here is an annotated, modern translation of Marcello Malpighi’s De Polypo Cordis, to which Kerckring is likely responding in his counter to the assertion that “polyps of the heart” develop in life. Kerckring corrects that what has been observed are post-mortum coagulations of blood. Aside from the issue of heart polyps, it was Malpighi’s microscope-aided, revolutionary observations of the fine organization of organ tissue in terms of “cells” which overturned the long-held view that organs such as the spleen, lungs or liver were simply colagulations (parenchyma) or a “confused lumps”, and Malpighi would respond directly to Kerckring’s Spicilegium : “De Polypo Cordis” (1666)

Line of Argument

The line of reasoning I will be following in this evidence might be called questions about the philsophy of seeing, as the dificulties of applying the microscope to anatomy attest, “seeing” is not a simple matter of “looking”. In order to assess how Spinoza concieved of the powers of the microscopes he built, one must take into view what micro-vision meant for those attempting it, in particular for those of a Cartesian conception of the world. Kerckring’s text gives a portal into the ambiguities of lensed vision, and the trust of observation.

A Sum on Spinoza Sugar

Spinoza at Sea

I’m waiting for Wolf’s book on the Canary Island Inquistion, so for now that should probably be all on the possible connections between the Spinozas and sugar production in Brazil and Barbados. It is my instinct that there is something there, that the bonds between the Amsterdam community and Recife, and also the wide-spread opportunity for short-term turn around would surely place some of Michael Spinoza’s investments in Brazil. It strikes me that the collapse of the Spinoza buisness upon Michael’s death is too immediate to not be due to either an erosion brought on by a decade of English harassment (as Jonathan Israel seems to suggest), or by Baruch’s incompetence. Rather, it would seem that as English naval attacks on Dutch shipping began in ‘51, Michael had already secured himself a fall-back within London in the person of Antonio Carvajal who petitioned many times on his behalf. The confiscated Brazilian sugar seized by the English ship George, already consigned by the Spinozas to de Morais in Rouen, suggests a substantial connection to Brazilian sugar, London and Rouen. Remember, Carvajal had strong connections to the Rouen community. When the Portgugeuse would retake Recife and send the Amsterdam community into a chaos of exiled immigrants, Michael Spinoza died. Significant would be his debt to the same Rouen merchant de Morais, to whom he had consigned sugar shipments. It would seem that the collapse of Recife, Sephardic sugar signaled the collapse of the Spinoza firm, and that Michael had leveraged himself too far. Baruch’s charitable donation of 5 guilders to the Brazilian poor in Brazil, at a time of personal financial difficulty, suggests a family connection to that community which may very well have been an economic one. 

The relevance of this for anyone looking into the motivations and principles going through Spinoza’s mind at the time of his break with the community, and his subsequent stand in politics and arguments for freedom, is that there may have been a substantial experience of colonial collapse, with an attendant association of messianic Judaism (in the roles of the Kabbalist Aboab da Fonseca and the political envoy Menasseh ben Israel), which sprang Spinoza forwards. Sugar, with its highly problematic ethical question of slave labor, perhaps lies on a fault line in the fortunes of the Spinoza family, not to mention his community. It is interesting that Spinoza would continue this Jewish connection to the English in his correspondence with Oldenburg the Royal Society Secretary, a philosophical and scientific continuation of the economic and cultural advantages his father and Menasseh were carrying out at the time of his expulsion. As his brother Gabriel seems to have followed firm connections to London and trade in his immigration to Barbados, Spinoza was seeking another kind of sugar.

Some general thoughts on the matter.