Passed over by the Berlin Philharmonic when they elected a chief conductor this year, Thielemann was compensated with the flimsy title of music director at Bayreuth, his spiritual home. Now 56, he has no known personal relationships and travels everywhere with his mother. A former long-term associate describes him as “the unhappiest man on earth”. So where, you are wondering, is the praise?

A new book, My Life with Wagner, (Weidenfeld, £25) has Thielemann’s name on it. He did not write it himself but approved a distillation of a summer’s Bayreuth conversations with a Wagnerite journalist, Christine Lemke-Matwey. Conductors do not write books to share bathroom-mirror truths, rather to impress us with their moral profundity. Barenboim, Boulez and Furtwängler are among the worst examples. Thielemann, by contrast, is revealing in unexpected and thought-provoking ways, not just about his inner self (which is not terribly interesting) but about a particular form of German amorality that seeks redemption in the objective contemplation of monstrous behaviour. Try this:

Wagner goes to the limits. His music dramas are full of murder and violence, incest, revenge, betrayal, obscenity, sexual subservience, none of them admirable things. Yet we go home after them feeling stronger. By projecting our fears on Wotan and his companions, we learn how life is played out.

Some strands of that thought are too horrendous to pursue to a logical conclusion. At face value, Thielemann is saying that art exists to stop us setting free the beasts in ourselves. We would all love to rape our sisters and burn the house down but, since Wagner does it for us, we don’t have to.

The conductor’s job is to bring the work close to perfection or the world will come to an end, just as Wagner said it would. Here’s Thielemann, again:

Sometimes I have nightmares. I dream that artistic quality is out of tune. I dream that art and music are destroying themselves because the quality has gone wrong. Because far too much that is trivial, empty, superficial and indifferent is rife, and is tolerated. And because none of us can find genuinely creative time to spare any more, either for ourselves or for such great work as Richard Wagner’s.

The world is a terrible place, says Thielemann. Since we can do nothing to improve human conduct, let us observe it from a safe theatrical distance and derive what comfort we can from our personal detachment and innocence. The greatest sin — nightmare — would be to neglect or distort great art, the only thing that might redeem us. Accept that the word is evil. Make good art.

This is not an original thought. Wagner wrote much the same in his long-winded essays. But, taken in a 21st-century context and with the benefit of Holocaust hindsight, it drives a deep shaft into an area of the German psyche where cultural achievement atones for past guilt. Karajan, a master of denial, applied music as a balm of oblivion. Thielemann, his apostle, preaches that art pardons all. Like many maestros, he conveys more than he knows. For this candour, let him be praised.