A brief explanation of Socrates' importance, in case you don't already know him. Many consider him the godfather of philosophy.
Socrates went around asking things we consider as common sense. He asked a General "What is courage?". The General told him it was when a soldier remained firm in battle. Socrates would reply: "No, you're just giving me an example. I asked you what is it?!" And so, talking to Socrates made you realize you knew nothing. Also, he didn't teach you, because he didn't know either.
His famous phrase was: I know that I know nothing. What he meant with this was the fact that you only can learn something if you realize beforehand that you know nothing about the topic. Otherwise, you wouldn't need to learn, right? He also taught us that The unexamined life is not worth living, because you must constantly review you actions in a rational way.
However, Socrates wasn't much appreciated by the masses. Not only did he made them look stupid, but the young people were beginning to question everything, and the men holding the power could lose it. At his trial, Socrates could have been freed if he payed the fine, his friends wanted to pay his fine, but he decided not to because that would be cowardly saving himself at the expense of others. He remained true to what he believed.