By James Naughtie
One of the greatest operatic tenors of his age, Placido Domingo, is making his British debut as a baritone in Verdi's Simon Boccanegra at London's Royal Opera House. It is but the latest move in the Spaniard's long and glittering career.
One of the great difficulties in opera is managing the balance between popularisation and artistry.
Everyone who sings or who cares about it (not to mention the conductors) wants to extend the reach of the music, in the knowledge that there is an audience out there that will find this stuff exciting and uplifting, the only trouble being that it hasn't yet been introduced to the secret.
But how far should you go in pretending that it's about "good tunes" in pursuit of a deeper enthusiasm? Step forward, Placido Domingo.
He was one of the Three Tenors at Italia '90, a formidable populariser of music for the operatic voice, but at the same time he is the artist whom opera houses around the world still treasure for his seriousness and his effervescent commitment to the craft of dramatic singing.
The point about Domingo is that he has managed that balance better than anyone else of his generation.
He is about to be 70, and still sings with a warmth and glorious tone that shows how carefully he has tended the voice.
Others have faltered, in pursuit of instant fame or celebrity. He is a magnificent survivor.
When I sat down with him the other day in his dressing room at the Royal Opera House, Covent Garden, he had just come off stage from a rehearsal of Verdi's Simon Boccanegra, in which he sings a role traditionally taken by baritones rather than tenors.
But, just as he began to sing heavier Wagnerian roles in the nineties to go with the flow of the feel of his voice, so he thinks it is just right now to sing this part.
This may not seem a big deal - but it is. The pressures of opera in the age of transcontinental productions and the fandango of the concert tour mean that it's sometimes difficult to be serious - to stop for a moment and to think how your voice should be protected, nourished, preserved.
Sometimes, it is too easy to pretend that nothing changes. Then one day you wake up and discover that the voice has gone, and opera managers at some of the great theatres around the world are not on the phone any more.
We talked about his decision to stop singing Otello in Verdi's opera, a part in which he was the undisputed modern master, and he said that for him it was entirely natural. The comfort and range of his voice was changing; it was time for new repertoire.
In an age when the big singers have a schedule that would have staggered and appalled their predecessors of a generation or two ago, this is a difficult decision to make.
The fact that he made it is why he is still singing on top form today and opening in Simon Boccanegra on Tuesday June 29th (there's a live BBC2 performance on the 10th, with relays to big screens in towns around the country on July 13th, and a semi-staged Prom - broadcast, of course, on BBC Radio 3 - on Sunday July 18th).
Here is a man who was under the surgeon's knife in March but couldn't wait to get back on stage.
Watching singers over many years, I've never seen anyone who comes closer to 'completeness' in opera - not only understanding the demands of the music (and taking them under his wing) but having an instinctive urge to make the drama work on stage.
Placido Domingo in Verdi's Simon Boccanegra
Without that, even the most delicate artistry never seems enough.
He sat in his dressing room, a long rehearsal behind him, waiting to see the director, Elijah Moshinsky, and wondering what he might say.
He enthused about Antonio Pappano, the extraordinary music director of the Royal Opera House and a dedicated Verdian, and about the Covent Garden audiences and the countless thousands who will see the production on the big screens and TV. This wasn't PR guff; it came from the heart.
Domingo is a rare bird indeed, still wedded to his art with all the old enthusiasm. It is good that he is still flying high.