According to Plato, the body is merely a holding cell for the soul here on Earth. The soul exists prior to life on Earth, and it will continue to exist following the death of the body. Prior to life, the soul has all knowledge, but at the moment of birth, this knowledge is concealed.
Plato's theory of the soul states that the soul embarks on a journey the moment it is formed. When the soul is created, it enters a preexistent state until the human is born and it can enter the body. The soul remains there until the body dies, at which point it enters yet another waiting period. When another human is born, it enters the new body and remains on Earth until the body perishes yet again. This cycle of life, death, and rebirth persists until the soul is perfected.
Plato believes that the soul is composed of three aspects: the rational, the spirited, and the desire.
The rational soul, Plato believes, is the part that should rule a human. The spirited soul constantly seeks approval, but is also the human drive to action. Lastly, the desire soul contains human emotions and the sex drive. Plato believes that the majority of mankind is ruled by the desire soul, which is why most humans are, therefore, unable to make good, moral choices. The only aspect of the soul that contains reason and can make good moral decisions is the rational soul.
As similar to Plato, Aristotle believes that the soul is composed of three parts: nutritive, sensitive, and rational. Plants, because they are living, contain the nutritive soul. Animals are capable of both living and sensing, and therefore, have both the nutritive and sensitive souls. Humans are more adept than both plants and...