We now possess four principles of morality: 1) a philosophical: do good for its own sake, out of respect for the law; 2) a religious: do good because it is God's will, out of love of God; 3) a human: do good because it will promote your happiness, out of self-love; 4) a political: do good because it will promote the welfare of the society of which you are a part, out of love of society having regard to yourself. But is this not all one single principle, only viewed from different sides?

Do not say hypothesis, and even less theory: say way of thinking.

There can hardly be a stranger commodity in the world than books. Printed by people who don't understand them; sold by people who don't understand them; bound, criticized and read by people who don't understand them; and now even written by people who don't understand them.

Never undertake anything unless you have the heart to ask Heaven's blessing on your undertaking.

What is the good of drawing conclusions from experience? I don't deny we sometimes draw the right conclusions, but don't we just as often draw the wrong ones?

Do not judge God's world from your own. Trim your own hedge as you wish and plant your flowers in the patterns you can understand, but do not judge the garden of nature from your little window box.

Everyone is a genius at least once a year.