Growth comes through analogy; through seeing how things connect, rather than only seeing how they might be different.

It is true that the grasping of truth is not possible without empirical basis. However, the deeper we penetrate and the more extensive and embracing our theories become the less empirical knowledge is needed to determine those theories.

A world government with powers adequate to guarantee security is not a remote ideal for the distant future. It is an urgent necessity if our civilization is to survive.

I believe serious progress (in the abolition of war) can be achieved only when men become organized on an international scale and refuse, as a body, to enter military or war service.

When the nazis came to power, I looked to the universities that prided themselves upon their intellectual freedom, and they failed me. I looked to the German press, which prided itself on the freedom of the press, and it failed me. Until at last the churches stood alone, and that for which I once had little regard earned my respect.

I believe that the first step in the setting of a real external world is the formation of the concept of bodily objects and of bodily objects of various kinds.

The most important method of education always has consisted of that in which the pupil was urged to actual performance.