The wonder of nature does not become smaller because one cannot measure it by the standards of human moral and human aims.

Dear Posterity, If you have not become more just, more peaceful, and in general more sensible... then may the Devil take you!

It's not that life has been easy, perfect or exactly as expected. I just choose to be happy and grateful no matter how it all turns out. If people are good only because they fear punishment, and hope for reward, then we are a sorry lot indeed.

I made one great mistake in my life-when I signed the letter to President Roosevelt recommending that atom bombs be made but there was some justification-the danger that the Germans would make them.

Science can only ascertain what is, but not what should be, and outside of its domain value judgements of all kinds remain necessary.

We cannot solve our problems with the same thinking we used when we created them.

Science is a wonderful thing if one does not have to earn one's living at it. One should earn one's living by work of which one is sure one is capable. Only when we do not have to be accountable to anybody can we find joy in scientific endeavor.