What counts can't always be counted; what can be counted doesn't always count.

The scientific theorist is not to be envied. For Nature, or more precisely experiment, is an exorable and not very friendly judge of his work. It never says "yes" to a theory. In the most favorable cases it says "Maybe," and in the great majority of cases simply "No." If an experiment agrees with a theory it means for the latter "Maybe," and if it does not agree it means "No." Probably every theory will some day experience its "No" - most theories, soon after conception.

It is easier to denature plutonium than to denature the evil spirit of man.

Man can find meaning in life only through devoting himself to society.

As soon as science has emerged from its initial stages, theoretical advances are no longer achieved merely by a process of arrangement. Guided by empirical data, the investigator rather develops a system of thought which, in general, is built up logically from a small number of fundamental assumptions, the so-called axioms. We call such a system of thought a theory. The theory finds the justification for its existence in the fact that it correlates a large number of single observations, and it is just here that the 'truth' of the theory lies.

The more cruel the wrong that men commit against an individual or a people, the deeper their hatred and contempt for their victim.

A great thought begins by seeing something differently, with a shift of the mind's eye.