I shall suggest, on the contrary, that all communication relies, to a noticeable extent on evoking knowledge that we cannot tell, and that all our knowledge of mental processes, like feelings or conscious intellectual activities, is based on a knowledge which we cannot tell.

Personal participation is the universal principle of knowing.

But even physics cannot be defined from an atomic topography.

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

A free society is regarded as one that does not engage, on principle, in attempting to control what people find meaningful, and a totalitarian society is regarded as one that does, on principle, attempt such control.

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.

I shall reconsider human knowledge by starting from the fact that we can know more than we can tell.