Man masters nature not by force but by understanding. - Jacob Bronowski

The Principle of Uncertainty is a bad name. In science, or outside of it, we are not uncertain; our knowledge is merely confined, within a certain tolerance. We should call it the Principle of Tolerance. And I propose that name in two senses. First, in the engineering sense: Science has progressed, step by step, the most successful enterprise in the ascent of man, because it has understood that the exchange of information between man and nature, and man and man, can only take place with a certain tolerance. But second, I also use the word, passionately, about the real world. All knowledge – all information between human beings – can only be exchanged within a play of tolerance. And that is true whether the exchange is in science, or in literature, or in religion, or in politics, or in any form of thought that aspires to dogma. It's a major tragedy of my lifetime and yours that scientists were refining, to the most exquisite precision, the Principle of Tolerance – and turning their backs on the fact that all around them, tolerance was crashing to the ground beyond repair. The Principle of Uncertainty or, in my phrase, the Principle of Tolerance, fixed once for all the realization that all knowledge is limited. It is an irony of history that at the very time when this was being worked out, there should rise, under Hitler in Germany and other tyrants elsewhere, a counter-conception: a principle of monstrous certainty. When the future looks back on the 1930's, it will think of them as a crucial confrontation of culture as I have been expounding it – the ascent of man against the throwback to the despots' belief that they have absolute certainty.

Science is a great many things, and I have called them a great many names; but in the end they all return to this: science is the acceptance of what works and the rejection of what does not. That needs more courage than we might think.

"We cannot separate the special importance of the visual apparatus of man from his unique ability to imagine, to make plans, and to do all the other things which are generally included in the catchall phrase "free will." What we really mean by free will, of course, is the visualizing of alternatives and making a choice between them. In my view, which not everyone shares, the central problem of human consciousness depends on this ability to imagine."