Then there are the fanatical atheists whose intolerance is of the same kind as the intolerance of the religious fanatics and comes from the same source.

The dog is very smart. He feels sorry for me because I receive so much mail; that's why he tries to bite the mailman.

I am neither especially clever nor especially gifted. I am only very, very curious.

Only six men in the world know about relativity. I am not one of them. When I ask them to explain, they confused me.

No path leads from a knowledge of that which is to that which should be.

It followed from the special theory of relativity that mass and energy are both but different manifestations of the same thing - a somewhat unfamiliar conception for the average mind. Furthermore, the equation E = mc², in which energy is put equal to mass, multiplied by the square of the velocity of light, showed that very small amounts of mass may be converted into a very large amount of energy and vice versa.

Everything that the human race has done and thought is concerned with the satisfaction of deeply felt needs and the assuagement of pain. One has to keep this constantly in mind if one wishes to understand spiritual movements and their development. Feeling and longing are the motive force behind all human endeavor and human creation, in however exalted a guise the latter may present themselves to us.