With “no alcohol, no renown, no women, no newspapers, no honours”, as he put it, he turned a modest existence on a professor’s pension into a life of holy poverty. “How at root he is a Christian,” Pourtalès writes, “this future anti-Christ!” Near the end in Turin, watching the passing cortège of a famous admiral, Nietzsche had the impression that he was attending his own state funeral. Accosting passers-by, he told them, “Be joyful. I am God. I am just in disguise.”

Nietzsche before the breakdown: In the 1880s, the ailing philosopher prophesied the West’s violent decline – but not even he could prevent it.