He justified the Soviet invasion of Hungary on the grounds that it quelled a nascent anti-Semitism. On the council of the Soviet-funded World Peace Organis- ation, Bernal shuttled all over Europe, and his understanding of thermonuclear war may have helped rein in Khrush- chev, whose ear he frequently had. However, at the very moment that Bernal was on the podium in Moscow, Khrushchev was despatching nuclear missiles to Cuba, so the case is not proven. Although he refused to condone the invasion of Czechoslovakia in 1968, Bernal said the Russians had been provoked by ‘reactionary forces ... acting on the orders of the American government’.

At Birkbeck, Bernal continued to work prodigiously. Although he missed the Nobel prize, narrowly, he continued to inspire others. Andrew Brown has drawn an impressive testimony to the achievements of Bernal’s flawed genius from Aaron Klug, Francis Crick, John Kendrew and many more. Max Perutz was amused by Bernal’s enthusiasm for economic planning because he was a ‘man who never planned anything. He was totally disorganised.’

Nobel laureate Sir Edward Appleton thought there were ‘two Bernals’, the peerless scientist and the political dupe. Andrew Brown subtly suggests that Bernal’s two sides were in fact connected: that his grand belief in the possibilities of X-ray crystallography was driven by passion as well as by intellect and that his communism showed only a different mixture of those two elements. In the end, Brown is himself too much a scientist to force a neat conclusion on to the amazing story of J. D. Bernal’s life and mind; but he takes us on a thrilling voyage and the reader is content to have been, in the better sense of the term, a fellow-traveller on that extraordinary journey.

Sebastian Faulks’ latest book, Human Traces, is published by Hutchinson, £17.99.

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