To make no mistakes is not in the power of man; but from their errors and mistakes the wise and good learn wisdom for the future. - Plutarch

A few vices are sufficient to darken many virtues.

When Demaratus was asked whether he held his tongue because he was a fool or for want of words, he replied, "A fool cannot hold his tongue."

When Darius offered him ten thousand talents, and to divide Asia equally with him, "I would accept it," said Parmenio, "were I Alexander." "And so truly would I," said Alexander, "if I were Parmenio." But he answered Darius that the earth could not bear two suns, nor Asia two kings.