and Plato Drawing on the words of his teacher Socrates, Plato considered the psyche to be the essence of a person, being that which decides how we behave. He considered this essence to be an incorporeal, eternal occupant of our being. Plato said that even after death, the soul exists and is able to think. He believed that as bodies die, the soul is continually reborn (metempsychosis) in subsequent bodies. However, Aristotle believed that only one part of the soul was immortal, namely the intellect (logos). The Platonic soul consists of three parts: the logos, or logistikon (mind, nous, or reason) the thymos, or thumetikon (emotion, spiritedness, or masculine) the eros, or epithumetikon (appetitive, desire, or feminine) The parts are located in different regions of the body: logos is located in the head, is related to reason and regulates the other part. thymos is located near the chest region and is related to anger. eros is located in the stomach and is related to one's desires. Plato also compares the three parts of the soul or psyche to a societal caste system. According to Plato's theory, the three-part soul is essentially the same thing as a state's class system because, to function well, each part must contribute so that the whole functions well. Logos keeps the other functions of the soul regulated. The soul is at the heart of Plato's philosophy. Francis Cornford described the twin pillars of Platonism as being the theory of the Forms, on the one hand, and, on the other hand, the doctrine of the immortality of the soul. Indeed, Plato was the first person in the history of philosophy to believe that the soul was both the source of life and the mind. In Plato's dialogues, we find the soul playing many disparate roles. Among other things, Plato believes that the soul is what gives life to the body (which was articulated most of all in the Laws and Phaedrus) in terms of self-motion: to be alive is to be capable of moving yourself; the soul is a self-mover. He also thinks that the soul is the bearer of moral properties (i.e., when I am virtuous, it is my soul that is virtuous as opposed to, say, my body). The soul is also the mind: it is that which thinks in us. We see this casual oscillation between different roles of the soul in many