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?

Experience without theory is blind, but theory without experience is mere intellectual play.

To be is to do.

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

To be is to do.

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

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

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.

But although all our knowledge begins with experience, it does not follow that it arises from experience.

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.

Happiness is not an ideal of reason, but of imagination.

Science is organized knowledge. Wisdom is organized life.

Intuition and concepts constitute... the elements of all our knowledge, so that neither concepts without an intuition in some way corresponding to them, nor intuition without concepts, can yield knowledge.