Gentlemen, let us suppose that man is not stupid. (Indeed one cannot refuse to suppose that, if only from the one consideration, that, if man is stupid, then who is wise?) But if he is not stupid, he is monstrously ungrateful! Phenomenally ungrateful. In fact, I believe that the best definition of man is the ungrateful biped.
Fyodor Dostoyevsky, Notes from Underground, White Nights, The Dream of a Ridiculous Man, and Selections from The House of the Dead
human-nature, man, stupidity