Do not destroy what you cannot create.

When a scientist says something, his colleagues must ask themselves only whether it is true. When a politician says something, his colleagues must first of all ask, 'Why does he say it?

You may assume infinite ignorance and unlimited intelligence.

Pronouncement of experts to the effect that something cannot be done has always irritated me.

I have been asked whether I would agree that the tragedy of the scientist is that he is able to bring about great advances in our knowledge, which mankind may then proceed to use for purposes of destruction. My answer is that this is not the tragedy of the scientist; it is the tragedy of mankind.

In science it is not enough to think of an important problem on which to work. It is also necessary to know the means which could be used to investigate the problem.

We turned the switch, saw the flashes, watched for ten minutes, then switched everything off and went home. That night I knew the world was headed for sorrow.