Socrates is credited with laying the foundation for Western philosophical thought. His "Socratic Method" involved asking
probing questions in a give-and-take which would eventually lead to the truth. Socrates's iconoclastic attitude didn't sit well with everyone, and at age 70 he was charged with heresy and corruption of local youth. Convicted, he carried out the death sentence by drinking hemlock, becoming one of history's earliest martyrs of conscience. Socrates's most famous pupil was Plato, who in turn instructed the philosopher Aristotle.