"The earth laughs in flowers."

"I have no taste for the pleasures of the senses, but I have a strong taste for the pleasures of the mind."

"The purpose of life is not to be happy. It is to be useful, to be honorable, to be compassionate, to have it make some difference that you have lived and lived well."

"Nature is no sentimentalist—does not cosset or pamper us. We must see that the world is rough and surly, and will not mind drowning a man or a woman, but swallows your ship like a grain of dust."

"The mind, once stretched by a new idea, never returns to its original dimensions."