Let us note . . . the radical difference between Aristotle’s view of concepts
and the Objectivist view, particularly in regard to the issue of essential
characteristics.
It is Aristotle who first formulated the principles of correct definition. It
is Aristotle who identified the fact that only concretes exist. But Aristotle
held that definitions refer to metaphysical essences, which exist in
concretes as a special element or formative power, and he held that the process
of concept-formation depends on a kind of direct intuition by which man’s mind
grasps these essences and forms concepts accordingly.
Aristotle regarded “essence” as metaphysical; Objectivism regards it as
epistemological.