Philosophy (from Greek: φιλοσοφία, philosophia, 'love of wisdom') is the systematized study of general and fundamental questions, such as those concerning existence, reason, knowledge, values, mind, and language. Some sources claim the term was coined by Pythagoras (c. 570 – c. 495 BCE), although this theory is disputed by some. Philosophical methods include questioning, critical discussion, rational argument, and systematic presentation.
Historically, philosophy encompassed all bodies of knowledge and a practitioner was known as a philosopher. "Natural philosophy", which began as a discipline in ancient India and Ancient Greece, encompasses astronomy, medicine, and physics. For example, Isaac Newton's 1687 Mathematical Principles of Natural Philosophy later became classified as a book of physics.