The major task of the twentieth century will be to explore the unconscious, to investigate the subsoil of the mind.

Laughter is the corrective force which prevents us from becoming cranks.

There are manifold tones of mental life, or, in other words, our psychic life may be lived at different heights, now nearer to action, now further removed from it, according to the degree of our attention to life.

The present contains nothing more than the past, and what is found in the effect was already in the cause.

We regard intelligence as man's main characteristic and we know that there is no superiority which intelligence cannot confer on us, no inferiority for which it cannot compensate.

I believe that the time given to refutation in philosophy is usually time lost. Of the many attacks directed by many thinkers against each other, what now remains? Nothing, or assuredly very little. That which counts and endures is the modicum of positive truth which each contributes. The true statement is, of itself, able to displace the erroneous idea, and becomes, without our having taken the trouble of refuting anyone, the best of refutations.

The motive power of democracy is love