@Victor Eremita,
God, I haven't thought of this in years. For Plato, I'd have to say everything that revolves around the death of Socrates, from his trial to his actual demise. I'd also go with
Leviathan. I read Wittgenstein,the Blue and Brown books, but I'll be damned if I remember anything about them any more so I think I'll leave 'em off.
Might add Will and Ariel Durant as that is an introduction for a lot of people.