Plato

Plato was twenty-eight years old when Socrates was put to death. Plato fell in with a wandering philosopher by the name of Socrates, of whom you may have heard, who encouraged his students to challenge conventional wisdom to the point that he was finally executed in 399 BC for corrupting the youth. This, Plato would say, was a major turning point in his life, and he fled Athens to avoid a similar fate by association. He wound up in Sicily, where he joined an order of Pythagoreans (something along the line of celibate math mystics), whose fixation with numbers would inspire the cosmology Plato would become famous for.

Based on ancient sources, most modern scholars believe that he was born in Athens or Aegina between 428 and 423 BCE.