It is by overcoming obstacles that man develops those qualities he needs.

Attaining consciousness is connected with the gradual liberation from mechanicalness, for man is fully and completely under mechanical laws.

A symbol may serve to transfer our intuitions and to suggest new ones only so long as its meaning is not defined.

One cannot keep all old views and opinions and acquire new ones.

The greatest barrier to consciousness is the belief that one is already conscious.

I mean that you always know what results will come from one or another of your actions; but in a strange way you want to do one thing and get the result that could only come from another

I have become so accustomed to think "scientifically" that I am afraid even to imagine that there may be something else beyond the outer covering of life. I feel like a man condemned to death, whose companions have been hanged and who has already become reconciled to the thought that the same fate awaits him.