But Aristotle and Aquinas differ on the nature of sensible things. Here’s an excerpt from Joseph Owens’s essay, “Aristotle and Aquinas,” (Chapter 2; The Cambridge Companion to Aquinas, edited by Norman Kretzmann and Eleonore Stump):
It is true that both Aristotle and Aquinas start from sensible things. To that extent they present a common ground upon which they may be judged. Through that ground their similarities may be explained. But in those external sensible things Aristotle sees finite form as the highest actuality. Aquinas, on the other hand, sees existence as the highest actuality. Existence of itself is not finite, since it is originally the object of a judgment and not of conceptualization. What is attained through conceptualization is, like the Aristotelian form, something finite. The notions table and red are both of finite objects in the judgment "The table is red." But can the same be said about what is known through the copula "is"? What is thereby grasped is of course not something infinite. It is something that just in itself escapes the characterizations of either "finite" or "infinite." Taken just in itself it is open to either, but it is finite when received into a limiting subject, as in sensible things, and infinite when subsisting as a nature.Aquinas was writing as a theologian, not as a philosopher—his agenda was to use Aristotelian theory to strengthen his theology. Therefore he had to differ with Aristotle on several issues.