Related:

• To arrive at perfection, a man should have very sincere friends or inveterate enemie
  because he would be made sensible of his good or ill conduct, either by the censures of the one, or the admonitions of the other....
• Friends were made for friends, and for people to argue with!!
• Men of sense often learn from their enemies. It is from their foes, not their friends, that cities learn the lesson of building high walls and ships of war .
  . . -- Aristophane...
• Sooth'd with the sound, the king grew vain; Fought all his battles o'er agai
  And thrice he routed all his foes, and thrice he slew the slain....
• Men like long nails - in old movies couples were always scratching each other's backs.
• If you want to avoid problems, never become good friends with an animal, since it lasts but a short while.
  On the other hand, never become friends with men, they last too long!...
• Even the best of friends cannot attend each other's funeral. -- Kehlog Albra
• His tribe were God Almighty's gentlemen.
  -- John Dryden (1631-1700) -- Absalom and Achitophel, Part i, Line 645...