Thucydides (c. 460-400 BCE)
“The fact is that when great prosperity comes suddenly and unexpectedly to a state, it usually breeds arrogance; in most cases it is safer for people to enjoy an average amount of success rather than something which is out of all proportion; and it is easier, I should say, to ward off hardship than to maintain happiness.”
- From a speech written by Thucydides in the character of Cleon in History of the Peloponnesian War (Book 3, section 39) by Thucydides, translated by Rex Warner (Penguin Classics, 1972).