we must always remember that the real content of evolution (biological as well as cultural) is the elaboration of new behaviour. - Jacob Bronowski

Human beings can imagine situations which are different from those in front of their eyes... because they make and hold in their minds images for absent things.

These are the moments when the powerful mind or the forceful character feels the ferment of the times, when his thoughts quicken, and when he can inject into the uncertainties of others the creative ideas which will strengthen them with purpose. At such a moment the man who can direct others, in thought or in action, can remake the world.

I have chosen to talk about one of the founder fathers of twentieth-century physics, Niels Bohr, because in both these respects he was a consummate artist. He had no ready-made answers. He used to begin his lecture courses by saying to his students, ‘Every sentence that I utter should be regarded by you not as an assertion but as a question’. What he questioned was the structure of the world. And the people that he worked with, when young and old (he was still penetrating in his seventies), were others who were taking the world to pieces, thinking it out, and putting it together.