Only the real, rare, true scientific minds can endure doubt, which is attached to all our knowledge.

We believe that civilization has been created under the pressure of the exigencies of life at the cost of satisfaction of the instincts.

It would be very nice if there were a God who created the world and was a benevolent providence, and if there were a moral order in the universe and an after-life; but it is a very striking fact that all this is exactly as we are bound to wish it to be.

Religion [is] the universal obsessional neurosis of humanity

Men are more moral than they think and far more immoral than they can imagine.

Thinking in pictures is, therefore, only a very incomplete form of becoming conscious. In some way, too, it stands nearer to unconscious processes than does thinking in words, and it is unquestionably older than the latter both ontogenetically and phylogenetically.

The voice of the intellect is a soft one, but it does not rest until it has gained a hearing.