ABSTRACT
Al-Kindi’s works are notable for the wide range of interests they display. In addition to works on metaphysics, psychology, ethics, and so on, which have attracted the most attention from modern scholars, he wrote treatises (usually in the form of epistles) in an astonishing variety of scientific disciplines. In subsequent propositions al-Kindi expands his account of how vision works. The visual rays that come from the eye form a cone, whose base is at the pupil. This allows him to explain why peripheral vision is weaker than vision of something directly in front of us. Philoponus’ stance towards Aristotle’s theory of vision is not unlike al-Kindi’s stance towards Euclid’s: he generally defends the Aristotelian account, but introduces certain original ideas, especially having to do with the propagation of light. Al-Kindi may even have supposed that the doctrine that light goes in all directions is orthodox Aristotelianism.
