What reasons does Plato give for thinking that there are three parts of the soul, the rational part, the appetitive part, and the spirited part. Once this picture of the soul is in place, how does it help Plato to make the case that the just soul is ruled by reason and is happy? Please use this source as main source: Plato, et al. "The Republic of Plato Translated into English with an Analysis and Notes.: Macmillan & Co., London (1950): 22-45  Must be 12 point, double spaced, times new roman