The first outline of The Ascent of Man was written in July 1969ａｎｄ　the last foot of film was shot in December 1972. An undertaking aslarge as this, though wonderfully exhilarating, is not entered lightly. It demands an unflagging intellectual ａｎｄ　physical vigour, a total immersion, which I had to be sure that I could sustain with pleasure; fｏｒinstance, Ihad to put off researches that I had already begun; ａｎｄ　I ought to explai-n what moved me to do so.

  There has been a deep change in the temper of science in the last20 years: the focus of attention has shifted from the physical to the life sciences. As a result, science is drawn more ａｎｄ　more to the study of in-dividuality. But the interested spectatｏｒis hardly aware yet how far-reaching the effect is in changing the image of man that science moulds. Asa mathematician trained in physics, I too would have been unaware, had not a series of lucky chances taken me into the life sciences in middle age. I owe a debt fｏｒthe good fortune that carried me into two seminal fields of science in one lifetime; ａｎｄ　though I do not know to whom the debt is due, I conceived The Ascent of Man in gratitude to repay it.

  The invitation to me from the British Broadcasting Corporation was to present the development of science in a series of television programmes to match those of Lord Clark on Civilisation. Television is an admirable medium- fｏｒexposition in several ways: powerful ａｎｄ　immediate to the eye, able to take the spectatｏｒbodily into the places ａｎｄ　processes that are described, ａｎｄ　conversational enough to make him conscious that what he witnesses are not events but the actions of people. The last of these merits is to my mind the most cogent, ａｎｄ　it weighed most with me in agreeing to cast a personal biography of ideas in the form of television essays. The point is that knowledge in general ａｎｄ　science in particular does not consist of abstract but of man-made ideas, all the way from its beginnings to its modern ａｎｄ　idiosyncratic models. Therefore the underlying concepts that unlock nature must be shown to arise early ａｎｄ　in the simplest cultures of man from his basic ａｎｄ　specific faculties. ａｎｄ　the development of science which joins them in more ａｎｄ　more complex conjunctions must be seen to be equally human: discoveries are made by men, not merely by minds, so that they are alive ａｎｄ　charged with individuality. If television is not used to make these thoughts concrete, it is wasted.