The further the spiritual evolution of mankind advances, the more certain it seems to me that the path to genuine religiosity does not lie through the fear of life, and the fear of death, and blind faith, but through striving after rational knowledge.

There is possibility in every difficulty.

I don't teach my students, I provide the circumstances in which they can learn.

For scientific endeavor is a natural whole the parts of which mutually support one another in a way which, to be sure, no one can anticipate.

A country cannot simultaneously prepare and prevent war.

The distinction between the past, present and future is only a stubbornly persistent illusion.

The whole of science is nothing more than a refinement of everyday thinking.