  The most important text on epistemology is al-Kindi’s best-known work apart from On First Philosophy, namely On the Intellect (Abu Rida 1950, 353–8; also McCarthy 1964, Ruffinengo 1997). This treatise has received an unusual amount of attention, despite its brevity and compressed argument, because it is the first Arabic work to show the influence of Greek taxonomies of the intellect into levels or types. (See especially Jolivet 1971, with Endress 1980.) These taxonomies, with various versions put forward by Alexander, Themistius, Philoponus and other commentators, were in turn attempts to systematize Aristotle’s remarks on intellect in De Anima book 3 and elsewhere.