Metaphysics deals with the basic nature of existence (i. e., reality). Contrary to a popular impression, it has nothing to do with the occult or with a hypothetical world beyond the plane of ordinary existence. The term was invented by an editor of the works of Aristotle, who treated the topic after ("meta" in Greek) his writings on physics. Epistemology, which we shall discuss first, deals with how we become conscious of reality—that is, with the nature of knowledge. Although we cannot explore every detail of these two areas, we need a basic grasp of them in order to develop a valid approach to understanding human action.