If Friedrich Nietzsche were alive today, what would he think of our times? “The nations are again drawing away from one another and long to tear one another to pieces,” he might observe. “The sciences, pursued without any restraint and in a spirit of the blindest laissez faire, are shattering and dissolving all firmly held belief; the educated classes and states are being swept away by a hugely contemptible money economy. The world has never been more worldly, never poorer in love and goodness … Everything, contemporary art and science included, serves the coming barbarism.”

That passage, from one of the philosopher’s “Untimely Meditations”, was published in 1874 and illustrates the extent to which Nietzsche is always our exact contemporary. The problem with writing books about him, though, is that you just can’t compete with the bleak hilarity and glamorous swagger of his prose, and to reduce the wild forest of his thoughts to single propositions in precis is nearly always to traduce him.

The American philosophy professor John Kaag tries a different tack, aiming to use Nietzsche as a kind of elevated self-help guru, scattering discussions of the philosopher’s life and works through a memoir of the author’s own youth and romantic life. This approach is defended early on by the claim that Nietzsche’s philosophy “is no mere abstraction. It isn’t to be realised from an armchair or the comfort of one’s home. One needs to physically rise, stand up, stretch, and set off.” It is surprising to see a professional philosopher talking of “mere abstraction” here. Few people today will stand up for abstraction, but it is a keystone of all intellectual endeavour, as Nietzsche himself well knew. “There are epochs,” he wrote, “in which the man of reason and the man of intuition stand side by side, the one fearful of intuition, the other filled with scorn for abstraction, the latter as unreasonable as the former is artistic.” (On Truth and Lying in a Non-Moral Sense, 1873.)

Friedrich Nietzsche,

circa 1890. Photograph: Hulton Archive/Getty Images

Abstraction having been thus derided, we set off nonetheless with the author to what you can’t get much less abstract than: mountains. Kaag tells us how, as a 19-year-old student, he went hiking in the Swiss Alps just as his philosophical hero had done: “Nietzsche came to the mountains to tread on the edge of the void.” Kaag stopped eating and nearly threw himself into a crevasse before coming to his senses. Then, 17 years later, he returns, this time with his wife – also a philosopher, but a Kantian who thinks Nietzsche “a marauding fool” – and their small daughter.

Unnecessarily, Kaag takes us through the airport as they set off on their trip, but the interest intensifies as we begin to breathe with his family the purer air of the mountains. They settle into a fine old hotel, and we hear about Nietzsche’s love affair with Lou Salomé, and accompany the author on a series of solitary hikes. “Christ, it was a long way to the bottom,” he remarks at one point. “Absolute certainty did not live up here.” We learn about his trousers and footwear, and there are good expository accounts of the major Nietzschean works, on tragedy, the genealogy of morals and so on. Kaag has a pleasingly wry, compact style, and is particularly interesting on thinkers that Nietzsche influenced heavily: Herman Hesse and Theodor Adorno.

The tone becomes more urgently confessional throughout Kaag’s book, as it becomes clear he is working through some sort of personal crisis – but if Nietzsche isn’t the man you want in a crisis, who is? Here in the Alps in 1881, near a pyramidal rock “6,000 feet beyond man and time”, is where he conceived of his most horrifying consolation: the idea of “eternal recurrence”. In the dead of night, he explained, a demon might whisper to you: “This life as you now live and have lived it you will have to live once again and innumerable times again; and there will be nothing new in it, but every pain and every joy and every thought and sigh and everything unspeakably small or great in your life must return to you, all in the same succession and sequence – even this spider and this moonlight between the trees.”

Nietzsche’s demand is that you should joyfully embrace such a prospect; indeed, to do so he calls the “highest formula of affirmation”. Kaag rather spoils the moment here by reducing this awful existential task to a version of the old metaphysical idea “that the movement of reality is best described in terms of cycles and epicycles”. But Nietzsche wasn’t making positive claims about the nature of material reality, he was throwing down a gauntlet; and we have still not picked it up.

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