The first forty years of life give us the text; the next thirty supply the commentary on it.

Virtue is as little to be acquired by learning as genius; nay, the idea is barren, and is only to be employed as an instrument, in the same way as genius in respect to art. It would be as foolish to expect that our moral and ethical systems would turn out virtuous, noble, and holy beings, as that our aesthetic systems would produce poets, painters, and musicians.

To desire immortality for the individual is really the same as wanting to perpetuate an error forever.

[T]he moralists of Europe [have] pretended that beasts have no rights... a doctrine revolting/gross/barbarous... on which a native of the Asiatic uplands could not look without righteous horror.

He who writes carelessly confesses thereby at the very outset that he does not attach much importance to his own thoughts.

Happiness belongs to those who are sufficient unto themselves. For all external sources of happiness and pleasure are, by their very nature, highly uncertain, precarious, ephemeral and subject to chance.

A man of business will often deceive you without the slightest scruple, but he will absolutely refuse to commit a theft.