Friendships are fragile things and require as much care in handling as any other fragile and precious thing.

Friendships are fragile things, and require as much handling as any other fragile and precious thing. -Randolph S. Bourne.

A man with few friends is only half-developed; there are whole sides of his nature which are locked up and have never been expressed. He cannot unlock them himself, he cannot even discover them; friends alone can stimulate him and open him.

Unreal friendship may turn to real
But real friendship, once ended, cannot be mended

If you have two friends in your lifetime, you're lucky. If you have one good friend, you're more than lucky.

In each of my friends there is something that only some other friend can fully bring out. By myself I am not large enough to call the whole man into activity; I want other lights than my own to show all his facets... Hence true Friendship is the least jealous of loves. Two friends delight to be joined by a third, and three by a fourth, if only the newcomer is qualified to become a real friend. They can then say, as the blessed souls say in Dante, "Here comes one who will augment our loves." For in this love "to divide is not to take away.