Now that we have seen and heard and wondered at Martinu's The Greek Passion in its original version - as it was, not as the musical establishment of the Fifties wanted it to be - it is really not so hard to see why the board at the Royal Opera 43 years ago should have back-peddled about staging it.
It is an extraordinary animal - untamed and unpredictable, wild, seemingly unco-ordinated, and yet of breathtaking restraint; a mystery play within a mystery play; part folk opera, part grand opera, speech mingling with recitative mingling with song, folk melody almost indivisible from the psalmody of the Greek Orthodox Church. There is nothing quite like it in the entire operatic repertoire.
But that was precisely the problem back in the Fifties. Martinu decided to rewrite. And his revisions (based on my experience of the recording) took the edge off the piece, polished that which was unhoned, rough-hewn, tightened and homogenised that which was in a state of flux. Martinu's music is naturally that way inclined. His orchestral writing sounds like it's been caught in a wind-tunnel, myriad fragments of raw matter whirring restlessly. But from the restless heart of his orchestra will suddenly emerge bountiful singing themes - as if all this raw matter has suddenly found form. That's what the score of The Greek Passion is all about: myriad musics searching for, and finding, a unifying purpose.
And like music, like drama. The novel, Christ Recrucified by Nikos Kazantzakis, on which the opera is based, examines our attitudes to the outsider - in this case a group of refugees from a Turkish massacre who seek asylum in a Greek village at the time of their Easter passion play. Slowly but surely the newly chosen protagonists begin to take on, in real life, the characteristics of their theatrical roles. With tragic consequences for the Christ figure, Manolios.
There is a marvellous defining moment in David Pountney's premiere production for the Royal Opera in which Katerina, the "merry" widow (typecast, of course, as Mary Magdalene) is ticked off by Panait, the local tanner, for offering the refugees food and water out of turn. "Judas!" she snaps, as if to acknowledge how well-suited he is to the role he is so reluctant to accept. And like a trap snapping shut, Martinu's drama and Pountney's production take hold.
It is played out in the manner of a shambling processional on one of the most exciting sets ever presented on the Covent Garden stage. How appropriate that a Greek, Stefanos Laziridis, should have designed it. It is many things, this set: a tree of life, a Tower of Babel, a crude cathedral, steep walkways linking a series of platforms which might be seen as Stations of the Cross. The central "trunk" reaches out of sight for the sky, the base - one might imagine - of a monstrous cross. From above hang great bells of burnished gold. As the curtain rises, they ring out their call to prayer. Below, a long table of Turks sit carousing - a kind of pagan last supper. Bold, primary imagery. There is a rough "communal" feel to Pountney's production which his huge and excellent cast and chorus seize upon.
The fragmentary nature of the piece - a flaw which Martinu turns into a virtue - lends urgency. No one strives to stand out but, as the passion play unfolds, individuals emerge. Timothy Robinson's Yannakos (the postman turned Peter), Robin Leggate's Panait (Judas), Gwynne Howell's Fotis (priest of the refugees), his natural dignity wonderfully deployed.
Marie McLaughlin is better than I've seen her in a long time as Katerina, and Jorma Silvasti's Manolios makes believable the enormous weight of responsibility placed upon him. It's not a great voice (the rapid vibrato makes for a slightly obtrusive colour), but it carries overwhelming conviction.
Everybody's words are laudably clear, the narrative so lucid that Martinu's decision to use a narrator figure now seems almost superfluous.
About three-quarters of the way through the evening I wondered if what the piece really lacked was a sense of climax. But then I realised. It builds quietly, this piece. Its power is in its restraint. By the end, it's a silent protest. Christmas comes, the snow falls, and the birth of the saviour brings hope for new beginnings. The refugees arrived at Easter, they leave at Christmas. Time to start again. And they leave through the auditorium. That's theatre. There are five more performances. Go.
Tonight, 7.30pm, Saturday and 3, 5, 8 May (020-7304 4000)