The first thing to make clear is that scientists, freely making their own choice of problems and pursuing them in the light of their own personal judgment, are in fact co-operating as members of a closely knit organization.

Discoveries are made by pursuing possibilities suggested by existing knowledge.

We know more than we can tell.

Our reliance on the validity of a scientific conclusion depends ultimately on a judgment of coherence; and as there can exist no strict criterion for coherence, our judgment of it must always remain a qualitative, nonformal, tacit, personal judgment.

So long as we use a certain language, all questions that we can ask will have to be formulated in it and will thereby confirm the theory of the universe which is implied in the vocabulary and structure of the language.

Personal participation is the universal principle of knowing.

We could not, for example, arrive at a principle like that of entropy without introducing some additional principle, such as randomness, to this topography.