The feeling of understanding is as private as the feeling of pain. The act of understanding is at the heart of all scientific activity; without it any ostensibly scientific activity is as sterile as that of a high school student substituting numbers into a formula. For this reason, science, when I push the analysis back as far as I can, must be private.

... the scientist would maintain that knowledge in of itself is wholly good, and that there should be and are methods of dealing with misuses of knowledge by the ruffian or the bully other than by suppressing the knowledge.

Coincidence is what you have left over when you apply a bad theory.

I can see no justification whatever for the attitude which refuses on purely a priori grounds to accept action at a distance ... Such an attitude bespeaks an unimaginativeness, a mental obtuseness and obstinacy.

If a specific question has meaning, it must be possible to find operations by which an answer may be given to it ... I believe that many of the questions asked about social and philosophical subjects will be found to be meaningless when examined from the point of view of operations.

Science is what scientists do, and there are as many scientific methods as there are individual scientists.

There is no adequate defense, except stupidity, against the impact of a new idea.