We can understand almost anything, but we can't understand how we understand.

Failure is success in progress

I do not believe in a personal God and I have never denied this but have expressed it clearly.

Concern for man and his fate must always form the chief interest of all technical endeavors. Never forget this in the midst of your diagrams and equations.

The most fundamental question we can ever ask ourselves is whether or not the universe we live in is friendly or hostile.

There is no greater satisfaction for a just and well-meaning person than the knowledge that he has devoted his best energies to the service of the good cause.

I cannot then believe in this concept of an anthropomorphic God who has the powers of interfering with these natural laws. As I said before, the most beautiful and most profound religious emotion that we can experience is the sensation of the mystical. And this mysticality is the power of all true science.