and Aristotle (1) and their disciples maintained that the species-essence of every individual is other than its particular existence.
They next disputed among themselves: Do those essences subsist independently of the existing persons? Plato claimed that they do, asserting that the essences are eternal and everlasting. These are what people call the Platonic Forms, the intelligible archetypes. His claim here resembles his view that matter exists on its own, apart from forms, and that void and time are two self-subsisting substances, independent of existing bodies and their attributes. His doctrine concerning prime matter, as well as duration, vacuum, and the specific realities, all proceeds from the same line of thought.
Aristotle—his companion—and those who followed him perceived that what Plato had asserted was nothing but an imaginative construct: absolute species, absolute matter, and absolute void. From this mental fancy he concluded that such things possess external existence, existing apart from these bodies and their qualities—just as their earlier teacher Pythagoras (2) had believed that numbers exist outside the mind and enjoy a reality distinct from the things that are numbered.
As for Ibn Sīnā (3) and others among the Arabs, although they trod the path of the apostates in following those misguided philosophers, they are cleverer than them and sounder in intellect and judgment, for they still possess, in general, a light from Islam by which they discerned much of those philosophers’ misguidance;