Huygens’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 [...]

The Hole at the “Center of Vision”

Spinoza as Seer In a sense, if we are to understand Spinoza’s optical influences we have to come to at least consider what seeing, or more helpfully, perceiving meant for Spinoza, for behind any optical conceptions Spinoza had lies the very act of actively engaging the world. Much as Descartes worked from definitive values of what [...]

The Ignored Letters of Spinoza

Equine In Thought I have been working for a few days on a commentary on two of Spinoza’s letters, which I will refer to as his Optical Letters. These two letters are Spinoza’s attempt to answer a question about optics and telescopes put to him by his friend Jarig Jelles. I just want to make a short note [...]

The Optica Promota and Spinoza’s concept of focus

Spinoza: Against Hyperbolic Vision There are several points of correspondence between Spinoza’s objections to Descartes’ treatment of the magnification of images in the L’Dioptrique in his letters 39 and 40, and the analyses found in James Gregory’s Optica Promota, but perhaps the most significant touching point occurs in Gregory’s conclusion, where he brings up the lone failings of parabolic mirrors [...]

Some Observations on Spinoza’s Sight

How The Two Philosophers “See” I feel that there are some important things to say about my recent post, A Diversity of Sight: Descartes vs. Spinoza , but I am still undecided just how deep the influence of these thoughts run. So pervasive is the metaphor of vision and light within Western metaphysics, any identification of an [...]

A Diversity of Sight: Descartes vs. Spinoza

Different Foci of “Clear and Distinct” This may be premature in my process, but I would like to set down some simple correspondences that have arisen in my reading of Kepler’s Paralipomena to Witelo (1604), correspondences that elicit strong tidal differences between Descartes’ approach to vision – with its attendant metaphysical counterpart, the clear and [...]

An origin of Spinoza’s “cones of rays” explanation, Letter 40

[addendum: in addition to these thoughts, the influence of a more recent source, James Gregory's Optica Promota (1663) has to be considered] Kepler and How Spinoza Viewed the Eye and Light As a point of reference it is important to locate the origin of Spinoza’s phrase “cones of rays” found in his letter 40, since [...]

Spinoza: Letter 40 and Letter 39

Below the pertinent, optically related passages from letter 40, for reference sake. Spinoza in this letter attempts to answer a follow-up question posed to him by his friend Jarid Jelles, regarding an answer he had already supplied in Letter 39. Both letters from Jelles are lost. The ultimate subject I take to be the seventh discourse of Descartes La [...]

Descartes’ Dioptrics 7th Discourse and Spinoza’s Letters 39 and 40

[For a fuller treatment of the topic read "Deciphering Spinoza's Optical Letters"] Telescopes and Turning a Flea into a Elephant To offer context to the question that Jelles poses in a letter we have lost, regarding the size of objects on the retina, I post here the likely text that Jelles has in mind, and to which Spinoza [...]

The Buttle Principle

A Beetle in the gears of knowing and the notion of the Press of the Mind Wittgenstein has a beautiful and striking analogy which he folds into his (No) Private Language argument. He compares any fact checking one would do in using a so called private language, to attempting to check for an error by buying several copies of the same edition [...]