Plato and Aristotle

In that painting… Plato is pointing toward the heavens, Aristotle is pointing toward the earth. Plato believed "essences" (the essential element of each thing in existence) came from the heavens, and what we saw were mirror images--of the gods.

Aristotle said essences were "in the things themselves." He meant it as if, someday, science could somehow extract that essential element. (Essences are concepts, i.e., in the mind, so we know that is as incorrect as Plato.)

"There is only one fundamental issue in philosophy: the cognitive efficacy of man’s mind. The conflict of Aristotle versus Plato is the conflict of reason versus mysticism. It was Plato who formulated most of philosophy’s basic questions—and doubts. It was Aristotle who laid the foundation for most of the answers. Thereafter, the record of their duel is the record of man’s long struggle to deny and surrender or to uphold and assert the validity of his particular mode of consciousness."
Review of J.H. Randall’s Aristotle,
The Objectivist Newsletter, May 1963, 18.

"No matter what remnants of Platonism did exist in Aristotle’s system, his incomparable achievement lay in the fact that he defined the basic principles of a rational view of existence and of man’s consciousness: that there is only one reality, the one which man perceives—that it exists as an objective absolute (which means: independently of the consciousness, the wishes or the feelings of any perceiver)—that the task of man’s consciousness is to perceive, not to create, reality—that abstractions are man’s method of integrating his sensory material—that man’s mind is his only tool of knowledge—that A is A.

"If we consider the fact that to this day everything that makes us civilized beings, every rational value that we possess—including the birth of science, the industrial revolution, the creation of the United States, even the structure of our language—is the result of Aristotle’s influence,...