is explained at length elsewhere, since the purpose here is to draw attention to the foundations of this argument.

This matter has been discussed extensively elsewhere, and both groups’ accounts of composition have been explained. One group claims composition from indivisible substances perceptible to the senses, namely indivisible atoms. The other claims composition from indivisible intelligible substances, as when they speak of species being composed of genera and differentiae, and bodies being composed of matter and form. Every composite necessarily requires a unit that is neither composite nor divisible.

It has been shown that the unit posited by either group has no reality in the external world; it is merely conceived in the mind.

Likewise, concerning the indivisible, immaterial intellectual substances they posit, such as the ten intellects, it has been shown elsewhere that these exist only in minds, not as concrete entities.

The oneness of the Beginningless, Eternal, Necessarily Existent Being—which, for both groups, amounts to denying His attributes—is far above such units and unities, which they affirm as existing externally although they have no reality except in the mind. Thus, their investigations ultimately led them to affirm the unity of existence and to maintain that existence is one. They do not distinguish between unity of kind and numerical unity.

Unity of kind is what is meant when it is said that existing things share what is denoted by “existence”; human beings share what is denoted by “human being”; animals share what is denoted by “animal”; and bodies share what is denoted by “body”—and so forth.