The Epicurean psychology assumes psychological hedonism as a theory of human motivation. Epicurus takes it for granted that humans are motivated to maximize their own pleasure and minimize their own pain . He adds to this the ethical hedonistic doctrine which asserts that they ought to so act. The problem knowing how to achieve this hedonistic end. Epicurus deduces from his hedonism that the pleasures we ought to pursue must be pure and not admixed with pain.
Psychological hedonism implies some desires are natural.
Unnatural desires, such as the desires for power or fame or wealth, lead to pleasure which are very impurely mixed with inevitable pains. Hence these desires are to be shunned. Fortunately natural and necess oppary desires are relatively easy to satisfy. Their satisfaction would produce the life most free of impure pleasures mixed with pain. The ideal state for the believer in Epicurean ethics would be a life of simple quiet pleasure.