In law a man is guilty when he violates the rights of others. In ethics he is guilty if he only thinks of doing so.
Science is organized knowledge. Wisdom is organized life.
Morality is not the doctrine of how we may make ourselves happy, but how we may make ourselves worthy of happiness.
Always recognize that human individuals are ends, and do not use them as means to your end.
By a lie, a man... annihilates his dignity as a man.
He who is cruel to animals becomes hard also in his dealings with men. We can judge the heart of a man by his treatment of animals.
All our knowledge begins with the senses, proceeds then to the understanding, and ends with reason. There is nothing higher than reason.
Experience without theory is blind, but theory without experience is mere intellectual play.
Seek not the favor of the multitude; it is seldom got by honest and lawful means. But seek the testimony of few; and number not voices, but weigh them.
To be is to do.