This exasperating book sets out to vindicate the stature of Wagner's Tristan and Isolde by looking at it principally via the philosophy of Immanuel Kant. On the first page, Kant is described as "the dry old sage of Konigsberg, for whom neither music nor the erotic had any evident appeal".
Everyone knows that Tristan contains some of the most erotic music ever imagined. So what on earth has Kant got to do with it?
Roger Scruton makes the perfectly just claim that no intellectual of Wagner's generation could afford to ignore Kant, not even Arthur Schopenhauer, the composer's greatest intellectual hero, who rejected just about every other philosopher. Never one to follow the crowd himself, and still relishing the prospect of defending the practically indefensible since his provocative attempt in the Los Angeles Times in the early 1990s to rehabilitate Senator Joe McCarthy as "a great American patriot", Scruton sets out to demonstrate that Wagner is "one of the great humanists of modern times".
Mainstays of his argument include a fairly standard account of Schopenhauer's reworking of Kant's transcendental idealism and the rather more exotic claim that in Tristan Wagner worked his way towards the earlier thinker's "philosophical anthropology" (Kant's own term for an a priori theory of human nature based on the proposition that humans see themselves as both subject and object) among other things via a correction of Schopenhauer's view of erotic love.
Schopenhauer explained the sexual act as an exertion of the species over the individual. But Wagner disagreed and sought to relocate its force - as no one can fail to hear in the ecstatic high points of Tristan - in the individual subject and in the object of desire.
From this quasi-Kantian premise, and the medieval idea of love as the "Godward-tending exaltation of the soul", it is only a small step to the notion that, through the individualising power of sex, one of Wagner's aims in Tristan was to recuperate the sacred in a secular world that no longer has much time for it.
Kant and Wagner join forces in Tristan , according to Scruton, in an anti-modernist sermon. Indeed, the more Scruton writes about it, the more this wonderful work hardens into a mere repository of moral values, rather like an inferior medieval text. Scruton's impressively erudite book is, I suspect, an example of what Georg Lukács called "triviality through profundity".
Scruton gets nowhere near the anguish of being-in-the-world and the fatal intoxication of sexual passion that saturate practically every note of Tristan . Nor does he agree that its disconcertingly bleak and disconnected moments are still more in tune with our perilous modern condition ("always five steps from the hospital", as Nietzsche put it) than a morally stiff-necked corrective to it.
Scruton's Tristan and Isolde and Wagner's are, I hope, entirely different things.
John Deathridge is professor of music, King's College London.
Death-Devoted Heart: Sex and the Sacred in Wagner's Tristan and Isolde
Author - Roger Scruton
Publisher - Oxford University Press
Pages - 238
Price - £17.99
ISBN - 0 19 516691 4