Philosophical Investigations is a highly influential work by the 20th-century philosopher Ludwig Wittgenstein. In it, Wittgenstein discusses numerous problems and puzzles in the fields of semantics, logic, philosophy of mathematics, philosophy of psychology, philosophy of action, and the philosophy of mind.

"I wanted very much to learn to draw, for a reason that I kept to myself: I wanted to convey an emotion I have about the beauty of the world."
Richard Feynman
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