Needham told me a wonderful anecdote about Mao Tse-tung. Mao asked him round one time in Peking and said he wanted Needham's advice about something urgent. Mao said he could not decide whether he should allow "his people" to have cars or whether he should make them stay on bicycles. What did Joseph think: which should it be? Mao couldn't think of any other Westerner with experience of cars to ask.
Joseph, who at home cycled all round Cambridge like a proper don, innocently remarked that he used a bicycle himself and found it very satisfactory. "Fine," said Mao, "then we'll stick with bicycles." The greenhouse effect was probably delayed by decades.
Joseph was the only person I have met who had a genuinely photographic memory. The perfect illustration of this is an astonishing story told to me by Peter Mitchell, the Nobel Laureate in Chemistry, who knew the Needhams well in the 1950s: "Doffy [Needham's first wife, Dorothy] told me one day that Joseph had a new hobby. He used to lie in bed in the mornings correcting his proofs [of Science and Civilisation in China] in his head. But he got tired of that, so now he lies in bed translating them into French first and then correcting them."