We need to really take that in, because it’s arguably the most famous sentence in Western philosophical thought. The only others that really come close would be René Descartes’s Cogito, ergo sum (“I think, therefore I am”), Thomas Hobbes’s “The life of man [is] solitary, poor, nasty, brutish, and short,” and of course the Insane Clown Posse’s “Water, fire, air, and dirt / Fucking magnets, how do they work?”