I am Dynamite! A Life of Friedrich Nietzsche. By Sue Prideaux. Tim Duggan Books; 464 pages; $30. Faber & Faber; £25.

“G OD IS DEAD! …And we have killed him!” Nietzsche put his most famous words into the mouth of a madman in “The Gay Science”, a book published in his late 30s. A decade later his work began to find readers, but by then he had himself gone mad, and sometimes thought he was God.

That mental collapse came on January 3rd 1889, when Nietzsche (above, in a portrait by Edvard Munch) was overwhelmed with pity for an abused horse in a street near his lodgings in Turin. There had been signs of trouble in his letters, and arguably in his boastful autobiography, “Ecce Homo”. Its megalomania notwithstanding, it provides a useful encapsulation of Nietzsche’s intellectual aims. These were to “unmask” Christian morality; to offer a “critique of modernity”; to show that “the old truth is coming to an end” and find ways of affirming life nonetheless.

Nietzsche died 11 years after the incident in Turin, sinking gradually into mental and physical paralysis. But while he sat mutely and played with dolls, his fame spread. In 1896 Richard Strauss composed his tone poem, “Also sprach Zarathustra”, named after Nietzsche’s best-known book. Mahler used words from the book in his third, partly choral, symphony. Thomas Mann, André Gide, W.B. Yeats and George Bernard Shaw were among those who regarded themselves as Nietzscheans.

He also had less savoury admirers, thanks in part to the efforts of his sister, Elisabeth Förster-Nietzsche, whom the sane Nietzsche came to dislike, especially when she married an anti-Semite. Nietzsche loathed German nationalism and anti-Semites—he thought Jews were part of the solution to the ills of modernity, not part of the problem. Elisabeth’s husband, Bernhard Förster, was the founder of Nueva Germania, a colony in the Paraguayan rainforest where some families from Saxony tried to show what Germans could achieve once they got far away from Jews.

Förster committed suicide in 1889; Elisabeth returned to Germany to look after her brother and then spent three and a half decades cultivating his literary legacy, especially among fascists. Mussolini sent her a birthday telegram in 1931 and Hitler laid a wreath before her coffin in 1935.

As Sue Prideaux (whose son works for The Economist) neatly puts it in her approachable biography of a usually forbidding man, Nietzsche’s emphasis on “the need to overcome ourselves became…distorted into the need to overcome others.” Whether he is culpable for making his ideas easy to mangle is debatable. Certainly no democrat, he had much to say about how the old order was decaying and perhaps too little about what could replace it.

Nietzsche had plenty to overcome in his own life, which is vividly recounted in Ms Prideaux’s wide-ranging and sensitive book. He suffered severe headaches and eye and stomach problems, and retired very early from his professorship in philology at Basel University. He was lonely both personally and professionally. And his key relationships, with Richard and Cosima Wagner, and with Lou Andreas-Salomé, did not end well. Nietzsche proposed twice to Salomé, who subsequently wrote books about him, as well as about Freud (of whom she became a disciple) and about the poet Rilke (with whom she had a long affair).

Yet there is joy in Nietzsche’s writing, too. It came from his long Alpine walks—“Never trust a thought that occurs to you indoors”—and from music. He turned to Bizet’s “Carmen” when Wagner’s “Tristan” lost its hold; it made him a better philosopher, he said. On the eve of his madness, Nietzsche wrote that without music “life would be a mistake.”