—and it is never anything but a determinate particular. Now, if someone contends that from the existence of the individual there follows the existence of the species and even of the genus (1), the consequent is not an unrestricted universal taken as such; rather, it is itself a determinate particular, one in whose very reality no two individuals can share, even though they may share in the same species. The cause that gives it its individuation and concreteness is the very cause that endows it with whatever attribute it bears, whether mere existence or necessary existence; and the same (2) is true of every member of a species—man, for example—for the cause that produces his very concrete reality is the same cause that produces in him his humanity, animality, and so forth. At this very point they, together with those who follow them, have gone into manifest error.

For when they say that the species “man” is predicated of both Zayd and ʿAmr, and that Zayd is not a man by his own essence—because, were he man by his essence, ʿAmr could not also be man, but rather it is due to a cause that made Zayd man and likewise made ʿAmr man—thus holding that the multiplicity of humanity results from multiplying the matter that receives it, and that its connection with matter is an effect and not intrinsic to the essence of humanity—this claim of theirs, which you relate with respect to metaphysics, natural philosophy, and logic, reveals its sophistry in several ways.

First: When they say, “Zayd is not man by his essence, for if he were man by his essence ʿAmr would not be man,” we ask them: By your statement “he is not man by his essence,” do you intend that something other than this concrete, existent man is thereby made man—as some of the Muʿtazilites allege when they say that the non-existent is a ‘thing’—or do you mean an absolutely universal essence shared alike by this man and others? Or do you mean by “his essence” this very particular, specified individual man? This division is exhaustive: the essence of this specific man is either identical with this man or it is something other than him; and if it is other than him, that other must either be a particular like him, matching him in specificity, or