ABSTRACT
Born in the Greek city of Stageira in 384 b.c.e., Aristotle became one of the most important teachers and philosophers of the ancient world. Aristotle primarily aims to investigate what he calls "being qua being"—"qua" meaning "by virtue of what is". But in the loose collection of ideas that make up Metaphysics, other subjects arise as well. Aristotle developed in Metaphysics is the theory of the "unmoved mover"—a kind of heavenly catalyst that serves as the source of all movement in the world. While a number of Aristotle's works have survived, even if he had written nothing but Metaphysics his reputation would be assured. His work has influenced philosophers throughout the centuries—from the ancient Greeks of his day to the Romans, to medieval philosophers in Christian and Islamic cultures. Aristotle's idea about the difference between substantial properties and accidental properties has inspired the modern theory of essentialism.
