So far this book has, perhaps, been suffocatingly materialistic. Money in and money out has been its theme. But most of the great inventors of history have not been conditioned in this way; selfinterest has not been their driving ambition. They have sought to help the community they live in, and the future they may never see, even though it has meant much personal self-sacrifice.

Some time ago I was sitting in the garden of Emmanuel College, Cambridge, on a summer evening looking again at the flowers, the pond and the ducks, that I had watched from the window of my rooms as a student. The flowers and the ducks were new, but little else had changed. Presently a very old man came wandering in and sat down beside me. Introducing himself, he said ‘My name is Jones – Melville Jones’. I told him my name and made small talk while I wildly searched my memory to connect up his name. Suddenly it dawned; my companion was Professor Sir Melville Jones FRS. I told him that he had taught me aeronautics a long time ago. I said ‘I still remember much of what you said’, and then, after a pause, I added ‘especially one sentence you said in a lecture. I apologise if I am being both silly and impertinent, but for some reason I can recall perfectly the way you said it.