ok. I should have seen this one earlier *breathes in*- sorry about lateness.
I'll explain this without biographical details, as you can find them, but I'll talk more about their philosophy.
Aristotle: 384-322BC. He tutored Alexander. Was a student and critic of Plato. His famous philosophy, the Nicomacean Ethics and Organon talks about pretty much everything, from metaphysics (our place in teh universe) to ethics (evaluation of human existence). A cool bit of info is his Doctrine of the Mean- "I should act not in excess, but in the mean".
Epicurus: 341-270 BC. Central to his philosophy was "pleasure as the root of human happiness"- there were 3 kinds of pleasure; necessary and natural, unecessary and unnatural, and unecessary and unnatural. NN = moderate food, drink, not being in pain. NU = sex, too much food, alcohol. UU = power, greed.
Plato: 427-347 BC. Taught by Socrates, studied with the students of Pythagoras. This guy thought in the middle- he didn't think much of metaphysics, or ethics, but thought a lot about politics. He liked justice and social harmony. A lot of his work was expressed through plays, very similar to Jesus' style of using parrables.
Socrates: 469-399 BC. Metaphysics was his main aim: "What am I? What is my life? Is there purpose?" He either wrote nothing, or it was all destroyed, so we have to read Xenophon to understand about him. I think there was a bit in Aristophanes' plays as well, as well as his student's Plato's stuff. He basically came to the conclusion that we'll never know anything, and said this to Athens. The polis got shitty at him, and condemned him to death, but he killed himself in the company of his friends.
Any other questions?