Plato's tripartite soul theory
-the parts are the rational part, the spirited part, and the appetitive part;
the three types of soul deal with the three parts
-a soul ruled by the appetitive part is inconstant and dangerous because each desire dominates the entire soul without limit
-the spirited part of the soul is not as dangerous, but it is not fully coherent and harmonised because the passions have no overarching guide
-a soul ruled by reason, however, is fully harmonised and just; it experiences desires and passions but only in the proper amounts and for the sake of rational ends