Anyone whom Allah Most High guides knows that existent things share nothing that actually exists within them. Rather, each existent is distinct in itself and in its attributes and actions. When we say, “This human being is alive and speaks,” or “is a rational animal,” or the like, his animality or rationality, or his speech and life, are not shared between him and anyone else. Rather, he has what is particular to him, and another has what is particular to that other. They resemble one another to the extent that their animality, rationality, and other attributes resemble one another.
If someone says that a human being is composed of that by which he shares something with others—animality—and that by which he is distinguished—rationality—then, if he means a mental composition, the claim is correct. For when we conceive a rational animal in our minds, animality is one part of this mental meaning and rationality its other part; and the animal component has more counterparts than the rational component. When we conceive what is designated by “animal” and what is designated by “rational,” the former encompasses human beings and others, whereas the latter is specific to human beings. Thus, the claim of composition in these mental meanings is correct. Yet this provides no fixed criterion. Rather, it depends on what a person conceives, whether that conception is true or false.
If by the part internal to a quiddity one means what enters into this conception; by its part external to it but necessarily accompanying its existence, what this expression signifies by inclusion and necessary implication; and by the whole quiddity, what it signifies by correspondence—then this is correct. But this does not entail that