Plutarch

"Silence at the proper season is wisdom, and better than any speech."

"Know how to listen, and you will profit even from those who talk badly."

"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."

"I don't need a friend who changes when I change and who nods when I nod; my shadow does that much better."

"What we achieve inwardly will change outer reality."