In the middle of difficulties lie opportunities.

In the middle of adversity there is great opportunity.

All the fifty years of conscious brooding have brought me no closer to answer the question, "What are light quanta?" Of course today every rascal thinks he knows the answer, but he is deluding himself.

We act as though comfort and luxury were the chief requirements of life. All that we need to make us happy is something to be enthusiastic about.

Do not worry about your difficulties in Mathematics. I can assure you mine are still greater.

The world is an evil place to live in. Not for those who do evil, but for those who sit back and allow evil to occur.

If I am right the Germans will say I was a German, and the French will say I was a Jew; If I am wrong the Germans will say I was a Jew and the French will say I was a German.