Friendship

Aristotle gave friendship two books of the Nicomachean Ethics, more than he gave justice, and distinguished three kinds: friendship for use, for pleasure, and for the friend's own sake. The first two last as long as the reason lasts; the third is rare and slow, and the only one he considered complete.

That threefold division explains why quotes about friendship often sound severe. They do not celebrate company so much as the test — what remains once the usefulness is gone. Cicero wrote a whole treatise on it after losing his closest friend, and his conclusion is uncomfortably simple: a single life contains very few real friendships, and that is fine.