Both Plato and Aristotle were primarily inter- ested in essences or truths that go beyond the mere appearance of things, but their methods for discovering those essences were distinctly differ- ent. For Plato, essences corresponded to the forms that existed independently of nature and that could be arrived at only by ignoring sensory experience and turning one’s thoughts inward. For Aristotle, essences existed but could best become known by studying nature. He believed that if enough indi- vidual manifestations of a principle or phenomenon were investigated, eventually one could infer the essence that they exemplified. In the opening pas- sage of his Metaphysics, Aristotle demonstrates that his attitude toward sensory information is much friendlier than was Plato’s.
■ Formal cause is the particular form, or pattern, of a thing. For example, a given piece of marble may be in the form of Aphrodite.
■ Efficient cause is the force that transforms the material thing into a certain form—for example, the energy of a sculptor.
■ Final cause is the purpose for which a thing exists. In the case of a statue of Aphrodite, the purpose may be to arouse pleasure in those who view it. The final cause is that for the sake of which something exists.