Science has gone a long way toward helping man to free himself from the burden of hard labor; yet, science itself is not a liberator. It creates means, not goals. It is up to men to utilize those means to achieve reasonable goals.

If I give you a pfennig, you will be one pfennig richer and I'll be one pfennig poorer. But if I give you an idea, you will have a new idea, but I shall still have it too.

I am content in my later years. I have kept my good humor and take neither myself nor the next person seriously.

As long as there will be a man, there will be wars.

When the solution is simple, God is answering.

A man's ethical behaviour should be based effectually on sympathy, education, and social ties and needs; no religious basis is necessary. Man would indeed be in a poor way if he had to be restrained by fear of punishment and hope of reward after death.

All means prove but blunt instruments, if they have not behind them a living spirit.