Philosophy is the study of the general and fundamental nature of reality, existence, knowledge, values, reason, mind, and language. The Ancient Greek word (philosophia) was probably coined by Pythagoras and literally means "love of wisdom" or "friend of wisdom". Philosophy has been divided into many sub-fields. It has been divided chronologically (e.g., ancient and modern); by topic (the major topics being  epistemology, logic, metaphysics, ethics, and aesthetics); and by style (e.g., analytic philosophy).