Descartes is considered by many to be the father of modern philosophy, because his ideas departed widely from current understanding in the early 17th century, which was more feeling-based. While elements of his philosophy weren’t completely new, his approach to them was. Descartes believed in basically clearing everything off the table, all preconceived and inherited notions, and starting fresh, putting back one by one the things that were certain, which for him began with the statement “I exist.” From this sprang his most famous quote: “I think; therefore I am.”