“In every department of physical science there is only so much science, properly so-called, as there is mathematics.”

“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.”

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

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

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

“Immaturity is the incapacity to use one's intelligence without the guidance of another.”

“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.”

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

“To be is to do.”

“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.'”