To exist is to change, to change is to mature, to mature is to go on creating oneself endlessly.

It is of man's essence to create materially and morally, to fabricate things and to fabricate himself. Homo faber is the definition I propose ... Homo faber, Homo sapiens, I pay my respects to both, for they tend to merge.

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.

There is nothing in philosophy which could not be said in everyday language.

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

It is with our entire past ... that we desire, will and act ... from this survival of the past it follows that consciousness cannot go through the same state twice. The circumstances may still be the same, but they will act no longer on the same person ... that is why our duration is irreversible.

Only those ideas that are least truly ours can be adequately expressed in words.