There are no rules for friendship. It must be left to itself. We cannot force it any more than love.
FRIENDSHIP, THERE ARE NO RULES FOR FRIENDSHIP
Friendship improves happiness and abates misery, by the doubling of our joy and the dividing of our grief.
FRIENDSHIP, FRIENDSHIP IMPROVES HAPPINESS
When the world is so complicated, the simple gift of friendship is within all of our hands.
You can always tell a real friend: when you've made a fool of yourself he doesn't feel you've done a permanent job.