This dissertation addresses an interpretive puzzle involving Plato’s apparently incompatible accounts of psychic conflict. I argue that a better understanding of the soul helps to resolve this puzzle, and that we can properly understand Plato’s conception of the soul by focusing on his account of self-mastery (τὸ κρείττω ἑαυτοῦ). Self-mastery is a concept well-suited to this project because it is treated consistently across Plato’s dialogues and features centrally in discussions of psychic conflict.