In 1936, I left my home town, Vienna, for Cambridge, to seek the Great Sage. He was an Irish Catholic converted to Communism, a mineralogist who had turned to X-ray crystallography: J.D. Bernal. I asked the Great Sage: ‘How can I solve the secret of Life?’ and he replied: ‘The secret of life is in the structure of proteins, and there is only one way of solving it and that is X-ray crystallography.’ So I became an X-ray crystallographer. We called him the Sage because he knew everything from history to physics. His conversation was the most fascinating of anyone I have ever come across. Actually, what had attracted me to Cambridge was not the Sage. It was the lectures of a young organic chemist in Vienna who told me of the work being done in the biochemistry laboratory headed by Gowland Hopkins, one of the founders of biochemistry.

Hopkins had shown that all chemical reactions in living cells are speeded up by enzymes. They are catalysed, chemists say. And he showed that all enzymes are proteins. The remarkable thing in the living cell is that chemical reactions go on at room temperature, in water, at near neutral pH. When chemists make these reactions happen, they need strong solvents or high pressures, or a vacuum, or strong acids and alkalis. In the living cell they take place without any of these, because there is a special protein that speeds up each particular reaction – and speeds it up by a fantastic amount.