"The ancient Aristotelian idea of friendship is that friends bring out the best in each other. Friends might have common backgrounds, similar affinities, like interests, but at its highest level friendship is about the formation and elevation of good character. Friendship that brings out corrupt or otherwise bad ends is, ipso facto, not true friendship.
Real friends, good friends in the Aristotelian sense, confer benefits on one another; or as Aristotle put it, 'It is more characteristic of a friend to do well by another than to be well done by, and to confer benefits is characteristic of the good man and of virtue.' In fact, one of the reasons for having friends, Aristotle believed, was to have people for whom to do good. That is why even the perfectly happy man needed friends, and why without them he was incomplete."
-Joseph Epstein, Friendship-