In the Republic, Socrates tells a story about a man who walking past a pile of bodies during the time of the plague in Athens. The man both wanted to look and wanted not to look. Eventually he gave in to his morbid desire and cursed his own eyes for wanting to see the terrible thing.
Socrates draws from this the conclusion that the human soul is not one thing but is divided into different things, or else how could someone want and not want something at the same time.
It occurs to me that this model of the soul can be mapped back onto the architecture of the brain as modern biology is describing it. Appetite, passion, and reason can be seen as progressively more advanced organs of the brain. Pain avoidance is, as is often said reptilian.