The genius of men like Newton and Einstein lies in that: they ask transparent, innocent questions which turn out to have catastrophic answers. The poet William Cowper called Newton a ‘childlike sage’ for that quality, and the description perfectly hits the air of surprise at the world that Einstein carried in his face. Whether he talked about riding a beam of light or falling through space, Einstein was always full of beautiful, simple illustrations of such principles, and I shall take a leaf out of his book. I go to the bottom of the clocktower, and get into the tram he used to take every day on his way to work as a clerk in the Swiss Patent Office.

[When] we practice science (and this is true of all our experience), we are always decoding a part of nature which is not complete. We simply cannot get out of our own finiteness.

We cannot hope to recapture today the terror that the mounted horse struck into the Middle East and Eastern Europe when it first appeared. That is because there is a difference of scale which I can only compare with the arrival of tanks in Poland in 1939, sweeping all before them. I believe that the importance of the horse in European history has always been underrated. In a sense, warfare was created by the horse, as a nomad activity. That is what the Huns brought, that is what the Phrygians brought, that is what finally the Mongols brought, and brought to a climax under Genghis Khan much later. In particular, the mobile hordes transformed the organisation of battle. They conceived a different strategy of war – a strategy that is like a war game; how, warmakers love to play games!