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.

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

There is no likelihood of our being able to suppress humanity's aggressive tendencies... Complete suppression of man's aggressive tendencies is not an issue; what we may try is to direct it into a channel other than that of warfare.

The price of civilization is instinctual renunciation.

Humanity is in the highest degree irrational, so that there is no prospect of influencing it by reasonable arguments. Against prejudice one can do nothing.

That which we can't remember, we will repeat.

Religion is a system of wishful illusions together with a disavowal of reality, such as we find nowhere else but in a state of blissful hallucinatory confusion. Religion's eleventh commandment is "Thou shalt not question."