Conceit may bring about one's own downfall.
Every man carries two bags about him, one in front and one behind, and both are full of faults. The bag in front contains his neighbors' faults, the one behind his own. Hence it is that men do not see their own faults, but never fail to see those of others.
Never trust advice from a man in the throes of his own difficulty.
If you allow men to use you for your own purposes, they will use you for theirs.
If you are a friend, why do you bite me so hard? If an enemy, why do you fawn on me?
Much wants more and loses all.