Socrates' pupil, made him hero of dialogues. Earthly objects mere copies of true, perfect forms in world of ideas. Can understand the ideas only through philosophy, i.e., pure reason. Physical body distracts mind, must be controlled to do philosophy. Soul leaves body after death, goes to wold of ideas, is reincarnated.
Ideas are universal truths based on reason.
Last hours of Socrates. Death is separation of soul from body, just what a philosopher wants. Proves existence of Ideas and recollection by soul through concept of equality, which is impossible to get from the senses. Therefore soul exists before body. Counters vague giving each his due, cynical might makes right and practicality arguments.