Human nature (n.) is not totally fixed, but on any realistic scale, evolutionary processes are much too slow to affect it.
Human nature (n.) is said to be "truck and barter," yet peasant societies ran for millennia without it, and no family haggles over who eats dinner.
Human nature (n.) is what capitalism calls the situations it had to force people into — and the forcing has had to go on to this day.
Human nature (n.) is a matter of pure intuition; science barely understands big molecules, so here anyone's guess is as good as anyone else's.
Human nature (n.) can easily turn any of us into efficient torturers — and that is irrelevant, since it equally yields selflessness, solidarity and great courage; you still stop the man beating a child.
Human nature (n.) can be bounded and still be infinite, just as the integers stay an infinite set though they leave out the rational numbers.
Human nature (n.) turns on two centres, around which all our pursuits revolve: to inquire and to create.
Human nature (n.) is so poorly understood that every sweeping social doctrine deserves suspicion, and so does every claim that human nature, efficiency or modern complexity requires some form of oppression.
Human nature (n.) lies at the core of everyone's politics: whoever calls a policy good for people has some picture of what people are, which a reasonable person tries to make clear.
Human nature (n.) obviously exists: whoever finds it absurd to say a granddaughter is no different from a rock or a salamander has already admitted it.
Human nature (n.) contains both saints and sinners, and every one of us carries the makings of each.