Kirk: Indeed, your greeting, not ours, lacked a certain benevolence.
Flint: The result of pressures which are...not your concern.
Kirk: Yes. Well, those pressures are everywhere in everyone, urging him to what you call savagery: the private hells, the inner needs and mysteries, the beast of instinct. As human beings, that is the way it is. To be human is to be complex. You can't avoid a little ugliness...from within and from without.