Just as a cautious businessman avoids investing all his capital in one concern, so wisdom would probably admonish us also not to anticipate all our happiness from one quarter alone.

Men have gained control over the forces of nature to such an extent that with their help they would have no difficulty exterminating one another to the last man. They know this, and hence comes a large part of their current unrest, their unhappiness and their mood of anxiety.

Where does a thought go when it's forgotten?

The adoption of the required attitude of mind towards ideas that seem to emerge "of their own free will" and the abandonment of the critical function that is normally in operation against them seem to be hard of achievement for some people. The "involuntary thoughts" are liable to release a most violent resistance, which seeks to prevent their emergence. If we may trust that great poet and philosopher Friedrich Schiller, however, poetic creation must demand an exactly similar attitude.

Dreams are constructed from the residue of yesterday.

Perception is less of a recording system and more of a protection system against external stimuli.

Neither in my private life nor in my writings, have I ever made a secret of being an out-and-out unbeliever.