[...] When Jean-Paul Sartre and Marcuse arranged to meet at the Coupole in Paris in the late 1960s, Sartre worried how he could get through lunch without revealing the truth. ‘I have never read a word Marcuse has written’, he told his future biographer John Gerassi. ‘I know he has tried to link Marx and Freud. And I know he supports activist students. But I can’t possibly read his books by next week. Besides I don’t want to stop my research on Flaubert. So you join us. And if Marcuse gets too philosophical, if he uses the word reification just once, interrupt and say something provocative and political.’

In the event, over cassoulet, Sartre came up with an ingenious strategy for concealing his ignorance. He asked questions that suggested a greater familiarity with Marcuse’s works than he actually had. ‘Each time he answered, I picked out an apparent flaw in his answer to ask another question. But since the flaw was only apparent, he could answer my question to his great satisfaction. Thus his vanity soared happily.’ Indeed it did: as Gerassi put Marcuse into a taxi, the latter ‘shook both of my hands with genuine gratitude and said: “I had no idea he knew my work so well.”’