Physical concepts are free creations of the human mind, and are not, however it may seem, uniquely determined by the external world.

An oligarchy of private capital cannot be effectively checked even by a democratically organized political society because under existing conditions, private capitalists inevitably control, directly or indirectly, the main sources of information.

I am an adherent of the ideal of democracy, although I well know the weaknesses of the democratic form of government. Social equality and economic protection of the individual appeared to me always as the important communal aims of the state. Although I am a typical loner in daily life, my consciousness of belonging to the invisible community of those who strive for truth, beauty, and justice has preserved me from feeling isolated.

Most of the fundamental ideas of science are essentially simple, and may, as a rule, be expressed in a language comprehensible to everyone.

External conditions can, to a certain extent, reduce, but never cancel individual repsonsibility.

A man's value to the community primarily depends on how far his feelings, thoughts, and actions are directed towards promoting the good of his fellows.

It is my conviction that pure mathematical construction enables us to discover the concepts and the laws connecting them, which gives us the key to the understanding of nature ... In a certain sense, therefore, I hold it true that pure thought can grasp reality, as the ancients dreamed.