Genuine morality is preserved only in the school of adversity; a state of continuous prosperity may easily prove a quick sand to virtue

Prosperity doth best discover vice, but Adversity doth best discover virtue

Prosperity discovers vice, adversity discovers virtue.

The historian is a prophet looking backwards.

Examine the lives of the best and more fruitful men and peoples, and ask yourselves whether a tree, if it is to grow proudly into the sky, can do without bad weather and storms: whether unkindness and opposition from without, whether some sort of hatred, envy, obstinacy, mistrust, severity, greed and violence do not belong to the favouring circumstances without which a great increase even in virtue is hardly possible. The poison which destroys the weaker nature strengthens the stronger – and he does not call it poison, either.

Do unto others 20% better than you would expect them to do unto you, to correct for subjective error.