As the world was expanding new ideas about life began forming like: " do we really exist"" or "where do we come from"." People started to study this along with human nature itself, and this was basically the whole idea of philosophy. It had probably been around for ages before the Greeks around the 6th century began organized, and really began studying it. There have been many, many philosophers since then that have tried to find the meaning of life and trying to study it and whatever secrets that we don't know yet and what-not. Some of the absolutely most important people in Philosophy were the Greeks from a few thousand years ago. Their teachings influenced us and most all of the people that came after them.

Some very influential philosophers were Socrates (469-399 BC), Antitheses (455-360 BC), Plato (427-347 BC), Diogenes of Sinope (400-325 BC), Aristotle (384-322 BC...