A Spider about

William of Auvergne’s Spider, 13th century, cause and belief

Thus the apprehension, as I said, of the spider with respect to the capture of the fly, is occasioned by the motion or concussion of a thread in his web, but it is effectively or efficiently caused by an innate light, or by an art naturally implanted in the spider. Just as you may see reminiscences and recollections issue forth from the habits of the sciences, and the virtues and vices, by the lightest stimuli of external occurances. This is seen in the example which Aristotle of the mental aptitude (solertia ), i.e., of the man who sees someone talking with the money-changer, and from this concludes that he wishes to get some money changed by him. Here this sight gives the occasion to the quick-witted mind, so that out of comes this thought, or suspicion. However, it is manifest that the view itself could not in itself be, in any way, the cause of this opinion or suspicion; on the other hand there is no doubt that there is something of an occasion, and that as a kind of help (adminiculum ) it favors the formation of the opinion. But the quick-witted is in itself the cause of the formation of the thought, which issues forth from it like an overflow, or like a stream from its source (trans. Moody).

De Universo