Abstract

In Book iv, Aristotle claimed that substance is prior to other beings, and he defends this claim by appeal to the doctrine of categories. Although the doctrine was not formulated with the metaphysical demands of Book iv in mind, these demands show that the doctrine is important in the study of being qua being, in so far that it isolates the basic subjects. Book iv did not tell which Aristotelian category the basic subjects would belong to; but in vii 1, Aristotle argues that they must belong to the category of substance.