For 99.9% of human history (and probably for 90% of people living today) thinking hard without some pressing need was a Bad Idea. The world was pretty much ste

For 99.9% of human history (and probably for 90% of people living today) thinking hard without some pressing need was a Bad Idea. The world was pretty much steady-state. Your survival depended on the good will of your family and community. And there was little margin for error, if whatever clever idea you thought up went badly wrong.