VISION, LIGHT AND COLOR IN AL-KINDĪ, PTOLEMY AND THE ANCIENT COMMENTATORS

Abstract

Al-Kindī was influenced by two Greek traditions in his attempts to explain vision, light and color. Most obviously, his works on optics are indebted to Euclid and, perhaps indirectly, to Ptolemy. But he also knew some works from the Aristotelian tradition that touch on the nature of color and vision. Al-Kindī explicitly rejects the Aristotelian account of vision in his De Aspectibus, and adopts a theory according to which we see by means of a visual ray emitted from the eye. But in the same work, al-Kindī draws on Philoponus’ commentary on Aristotle's De Anima. His borrowing from this commentary, via an Arabic paraphrase of the De Anima, was crucial in the development of al-Kindī's new ‘ ‘ punctiform analysis of light.” Conversely, two broadly Aristotelian works by al-Kindī, which explain the reason things are colored, engage with problems about color dealt with in the Aristotelian tradition ( e.g. by Alexander of Aphrodisias ). But here the Aristotelian theory, and in particular the Aristotelian notion of the transparent, is abandoned in order to accommodate the visual ray theory expounded in De Aspectibus.