“A categorical imperative would be one which represented an action as objectively necessary in itself, without reference to any other purpose.”

“All our knowledge begins with the senses, proceeds then to the understanding, and ends with reason. There is nothing higher than reason.”

“All the interests of my reason, speculative as well as practical, combine in the three following questions: 1. What can I know? 2. What ought I to do? 3. What may I hope?”

“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.”

“Even philosophers will praise war as ennobling mankind, forgetting the Greek who said: 'War is bad in that it begets more evil than it kills.'”

“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.”

“I had therefore to remove knowledge, in order to make room for belief.”

“If man makes himself a worm he must not complain when he is trodden on.”

“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.”

“Ingratitude is the essence of vileness.”

“It is beyond a doubt that all our knowledge begins with experience.”

“It is not God's will merely that we should be happy, but that we should make ourselves happy.”

“It is not necessary that whilst I live I live happily; but it is necessary that so long as I live I should live honourably.”

“Live your life as though your every act were to become a universal law.”

“May you live your life as if the maxim of your actions were to become universal law.”

“Metaphysics is a dark ocean without shores or lighthouse, strewn with many a philosophic wreck.”

“Morality is not the doctrine of how we may make ourselves happy, but how we may make ourselves worthy of happiness.”

“Out of timber so crooked as that from which man is made nothing entirely straight can be carved.”

“Religion is the recognition of all our duties as divine commands.”

“Science is organized knowledge. Wisdom is organized life.”

“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.”

“Thoughts without content are empty, intuitions without concepts are blind.”

“To be is to do.”

“Two things awe me most, the starry sky above me and the moral law within me.”

“What can I know? What ought I to do? What can I hope?”