Teaching should be such that what is offered is perceived as a valuable gift and not as hard duty. Never regard study as duty but as the enviable opportunity to learn to know the liberating influence of beauty in the realm of the spirit for your own personal joy and to the profit of the community to which your later work belongs.

As our circle of knowledge expands, so does the circumference of darkness surrounding it.

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

When a blind beetle crawls over the surface of a globe he doesn't notice that the track he has covered is curved. I was lucky enough to have spotted it.

I have never belonged wholeheartedly to country or State, to my circle of friends or even to my own family... Such isolation is sometimes bitter, but I do not regret being cut off from the understanding and sympathy of other men. I lose something by it,to be sure, but I am compensated for it in being rendered independent of the customs, opinions and prejudices of others, and am not tempted to rest my peace of mind upon such shifting foundations.

We must be prepared to make the same heroic sacrifices for the cause of peace that we make ungrudgingly for the cause of war.

The most practical solution is a good theory.