The document discusses different philosophical perspectives on the self and identity. It describes the views of several prominent philosophers including: Socrates, who said people should know themselves; Plato, who saw the soul as having rational, spirited, and appetitive parts; Augustine, who viewed humans as having both imperfect earthly and perfect immortal aspects; and Descartes, who argued "I think therefore I am" and saw the self as the mind separate from the body. Later philosophers discussed include Hume, Kant, Ryle, and Merleau-Ponty.