The theory must not contradict empirical facts.

Numerous are the academic professors, but rare are wise and noble teachers.

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.

Without creative, independently thinking and judging personalities the upward development of society is as unthinkable as the development of the individual personality without the nourishing soil of the community.

A perfection of means, and confusion of aims, seems to be our main problem.

No fairer destiny could be allotted to any physical theory than that it should of itself point out the way to the introduction of a more comprehensive theory, in which it lives on as a limiting case.

True knowledge comes with deep understanding of a topic and its inner workings.