Friendship like love is but a name,
Unless to one you stint the flame.
The child, whom many fathers share,
Hath seldom known a father's care.
'Tis thus in friendships; who depend
On many, rarely find a friend.

Gay

There must be many a pair of friends
Who, arm in arm, deserve the warm
Moon-births and the long evening-ends.
So, for their sake, be May still May!

Robert Browning

When two friends part, they should lock up each other's secrets and exchange keys.

Anon