Michael Tanner, who died last week, had such a vital mind and stood so far above the common run of music critics, that it’s hard to believe that he’s gone. For a philosopher to concern themself with the inner game of opera is not unknown (think of Friedrich Nietzsche and Roger Scruton). To do it as perceptively and as readably as Tanner is rarer. For two decades from 1996, his weekly Spectator opera column offered as thorough and as stimulating an education in musical aesthetics as one could hope to receive; intellectual red meat served with forensic clarity and a mischievous, subversive smile.

I don’t know what I expected when, after 15 years as a reader, I invited him to speak to a pre-concert crowd in Birmingham about Beethoven’s Ninth Symphony. Michael arrived wearing jeans and a leather jacket, walked straight on without notes and delivered a 30-minute précis of Thomas Mann’s Doktor Faustus, which gradually evolved into a panorama of the Ninth’s precise significance not just in music, but across two centuries of European history and culture. You could almost hear the audience’s brains buzzing as they left.

An hour later we were still standing in New Street, locked in what – for him, I’m sure – was just a casual conversation about Wagner; which for me was worth three years of Oxford tutorials. When I, too, started writing opera reviews for the Spectator, it was as a stopgap while Michael explored his many other interests. He must have been nearly 80 at that point (I would have placed him in his mid-sixties) but until recently it always felt as if I was simply minding his column until he was ready to come blazing back. It was understood that he had first pick of the operas; and they were gladly conceded because Michael’s thoughts, whether on Parsifal or The Merry Widow, were more worth having than those of anyone else alive.

I knew very little of Michael’s personal life, his remarkable academic career, or the legendary Wagner evenings that he hosted in his rooms at Corpus Christi, Cambridge, but I can, perhaps, try and describe what made him our greatest living opera critic. First: his clarity. Academic musicology has evolved a mandarin style so formulaic that there’s even an online bot spewing the stuff out on Twitter (‘In contrast to mensuration canon, the all-interval tetrachord is not, despite conventional wisdom, humorously irrelevant’).

But Tanner was not a musicologist (some of them seem to have resented that), and he expressed complex ideas in humane, droll, jargon-free English. Here he is, opening the door straight into his 1995 book Wagner:

What is it about Richard Wagner that makes him, 112 years after his death, still so violently controversial? The easy answer would be ‘everything’ but it would not be quite right…

If you believe that good writing emerges from clear thinking, Tanner’s columns and his books (two on Wagner, as well as equally lucid introductions to Nietzsche and Schopenhauer) are the QED. With clarity goes economy: the 1995 Wagner deals with the master’s complete works, and conducts profound and searching interrogations of their meaning, in just 225 pages. You can slip it in your back pocket when you go to the opera. I regularly do, and if after a Wagner opera you find yourself alone and desperate for a discussion, Tanner is waiting in its pages, anticipating exactly what you wanted to ask and ready to agree, dispute and elucidate. It’s a gem, a classic; the one truly indispensable book on Wagner for the intelligent general reader.

That’s the next thing: Tanner was not a professional musician, and he knew that opera was far too important to be left to the professionals. ‘There are no musical technicalities in this book, which means that it is not an explanation of how Wagner gets his effects, but rather an explanation of what they are’, he explains at the start of Wagner. And bang! Like Donner at the end of Das Rheingold, he’s dispelled the fog that stands between the art and its meaning.

No need, with Tanner, to memorise catalogues of leitmotifs and their supposed functions (there isn’t a scrap of music notation in the book). There’s no laboured technical analysis, no biographical obfuscation. He could do all that in his sleep, of course; but he was more interested in what art says to us. Each week he discussed opera as (his own words) a ‘mixed art form’: a dramatic experience in which music is fundamental but never, in itself, sufficient. True, no-one cherished great singing more (he joked that he’d once proposed marriage to the soprano Astrid Varnay). He was wholly uninterested in opera as a glorified concert. He sought drama as Wagner and the ancient Greeks understood it; a union of art forms that transcended the sum of its parts. He was as likely to find it in a Gloucestershire chicken-shed – Longborough Festival Opera  – as at Covent Garden or even (maybe especially) at Bayreuth.

That irritated some fellow-critics, and certainly the opinions of a writer who took art as seriously as most people (and many artists) merely claim to, could feel brutal. ‘Unrelieved musical inflammation, with frequent burstings of the boil and deluges of musical pus before the next one starts accumulating’ was his unforgettable description of an opera by Korngold that I happened to like (we differed over Turandot, too). Later, I came to appreciate that even Michael’s most enjoyably savage slatings originated in a belief that opera genuinely mattered: that good and bad art could, and must, be distinguished; that cynicism, groupthink or even well-meaning mediocrity should be identified and exposed.

Classical music journalism is a timid, genteel profession, and much of what gets printed is little more than PR. Tanner never let his admiration for artists divert him from the honesty that he owed to his readers and to art. That seemed shocking to some but many more, I suspect, found it intensely stimulating. One obituary described him as ‘waspish’, but my experience was of a generosity and a professional respect which – compared to Michael’s own achievements – I had done very little to earn.

He grilled me once over something foolish that I’d written about Gilbert and Sullivan: a facile, throwaway bit of phrase-making. I shrank inwardly: he’d found me out. But no. As he listened to my excuses and continued to ask questions, I realised that he was taking my flippant remark entirely seriously. More than that; he was sincerely curious to hear a perspective that he had not previously considered. I didn’t have one, and I’ve rarely felt more humbled, but then, I’d never argued with an actual philosopher. This must have been how Socrates’s contemporaries felt when he stopped them in the streets of Athens.

Michael Tanner was a life-force. His work – all that profundity, all that wit, all that glorious invective – was driven by a zest for ideas; a hunger to learn about his fellow-humans (even a flat-footed rookie journo) and to explore the full richness of what art and thought can offer us. He argued and wrote with all his might, but always honestly and always in good faith. As he leaves us, that, perhaps, is what we need – and will miss – the most.