"In the first place, [men] think about problems that there is absolutely no need for them to solve so far as their biological needs, their struggle for survival, are concerned: the problems of mathematics, the problems of philosophy, the problems of any of the theoretical or speculative sciences. And in the second place, the manner in which they think about those problems is quite different. An animal, when thinking about or solving a problem, is active. He uses his senses, uses his limbs, runs around. But a man thinks in a different manner. You all I’m sure have the image of the human thinker. It is given us by that statue of Rodin’s which is here in San Francisco, Le Penseur. If you think about that famous statue, I want you to notice something. There is the posture of human thought. And what you see about that posture is intense bodily inactivity. Only men sit down to think about what is important and not urgent."
[Mortimer Adler, How to Think about the Great Ideas]