The world can only be grasped by action, not by contemplation. The hand is the cutting edge of man. - Jacob Bronowski

The world can only be grasped by action, not by contemplation.

There are many gifts that are unique in man; but at the centre of them all, the root from which all knowledge grows, lies the ability to draw conclusions from what we see to what we do not see, to move our minds through space and time, and to recognise ourselves in the past on the steps to the present. All over these caves the print of the hand says: ‘This is my mark. This is man.

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.

We cannot change our character, we can only enlarge it. If we are wise, then we go on learning all through life, and go on fitting what is new to what we have learnt before, piece by piece.