For two of the last century’s greatest artists that they shouldn’t have collaborated more often is perhaps unusual – though Bernstein didn’t conduct opera as often as he might have. Bernstein’s own ambivalence towards Wagner – “I hate Wagner, but I hate him on my knees” – meant he would never conduct at Bayreuth either, even though he had suggested that he would indeed lead a new production of Tristan und Isolde there in 1972 (that never materialised, and Carlos Kleiber conducted the next Bayreuth Tristan in 1974).

Bernstein would conduct Tristan und Isolde, of course, in Munich. That performance, recorded live an act at a time over several months, would unlikely have been to Nilsson’s tastes. Indeed, in the over three decades since it was made this is a recording of Tristan that has sharply divided critical opinion – and continues to do so. For some, the extremely slow tempi, especially for the first two acts, which are among the longest on record, make this performance dramatically weak, even incoherent; for others, that very slowness reveals power and sumptuousness in equal measure. It begins with a Prelude of astonishing breadth – but Bernstein’s is by no means as unique as one might think. Fritz Reiner, in a live performance with the Chicago Symphony Orchestra from the 1957/58 season of concerts, is as breathtakingly expansive as Bernstein is. What both Bernstein and Reiner amply demonstrate – where a conductor like Carlos Kleiber sometimes doesn’t – is that this music is organic; the pauses and bar rests are part of the music, not distinctly separate from it. When Karl Böhm commented that Bernstein dared to conduct Tristan as Wagner wrote it he wasn’t being altogether facetious, nor uncomplimentary – though Böhm rarely took his own advice. The one compelling reason to listen to Bernstein’s performance is almost symmetrically similar to the reason why one should listen to Toscanini’s 1930’s Wagner: What might be excessive control of the music to some ears, is revelatory to others.

This is not to say that Bernstein’s Tristan is not beset by problems because it obviously is. The major disadvantage is that this is not a single performance of the opera. It doesn’t lack drama – far from it – but it’s drama that’s not consistent with our assumptions about opera in the theatre. An audio recording by itself can rarely give us a picture of a live event; film, on the other hand, is entirely impressionistic. If some find Bernstein’s Tristan antithetical to this opera’s drama and intensity there’s more than enough ammunition here to help justify those claims. Compare it to, for example, the great Böhm/Nilsson/Vickers Tristan from Orange in 1973 and Bernstein’s Tristan can be seen as an exercise in stasis: The singers rarely move, there is no staging to speak of; the music and the voices build everything into an evolving drama. And the orchestra is the fulcrum from which almost everything is built up. In one sense, this is a Tristan - semi-staged, though even that is a generous description – that alludes to the theatricality of some Pinter or Beckett; it’s microscopic, even absurdly, interventionist in an opera that ideally requires the opposite.

The film of this Tristan is revealing in one sense in that it lets us see the conductor – and Bernstein looks on the verge of a nervous breakdown after Act I – but in no sense does this at all seem obvious from the Philips audio recording. The physical exhaustion is so palpable it now perhaps seems inevitable the opera was performed this way. But when you listen to Act I Bernstein’s symphonic way with the score, with swelling and wildly vivid chords, with waves of sound almost breaching the limits of Wagner’s scoring, the scale seems more imposing than usual, too. Bernstein’s Tristan is rather similar to standing in front of Gericault’s Raft of Medusa at The Louvre: A shipwreck of a performance almost certainly, but you’re drawn into its psychological and disturbing complexities in the way that great visual art often engulfs you. It’s little more than an exercise in power, however: This is the art of control, deliberately indulgent as no other performance of Tristan is.

One of the glories of these concerts was the translucent, and languid, playing of the Bavarian Radio Symphony Orchestra. I think it’s always seemed unlikely that such disciplined, detailed and unfailingly beautiful playing could have ever been achieved from either an orchestra pit, or over the period of a single performance. Bernstein’s attention to detail is microscopic – the phrasing is often so precise, the bar rests so eternal, the emphasis on sound so important that this Tristan is often pulled in two distinct, and opposing, directions. The passion that Bernstein gets is so symphonic that he’s forgotten about the voices.

And those voices are not at all even. Hildegard Behrens’s Isolde is on the light side, more fragrant and fragile than one would ideally like. The voice rather lacks backbone, notably in the bottom register, but it’s a good match for her Tristan, sung by Peter Hofmann. Behrens would, in a few years or so, become a fine Isolde – but here she is rather constrained by the slowness of the music to give us an Isolde that is dreamy rather than dramatic, reflective rather than vituperative. Hofmann’s Tristan was never comparable to the best on record, or in the opera house – and he doesn’t really, unlike his Isolde, seem to benefit from the single-act concept; indeed, one might argue he’s actually hindered by it, especially in Act III. Hofmann never really feels a convincing Tristan because the scope of Tristan’s full tragedy is rarely allowed to develop. True, there are no wiry moments, no rough edges to Hofmann’s Tristan – though his tone, rather than feeling refreshed between each act struggles to achieve any depth. His long monologues in Act III are often uneven, and there is little in the sense of molten intensity. Bernstein picks up speed in Act III – a notably faceless prelude beginning it – but even so when Behrens and Hofmann sing together, such as in the Liebesnacht, the effect really isn’t as intended.

There are some advantages from a sound perspective to this Blu-ray version of Tristan und Isolde. The Philips CDs emphasise the orchestral balance in the BRSO’s favour even more starkly than is the case here. If the audio of the performances suggest that Bernstein had immersed his singers under great waves of sound, the film somewhat corrects that impression. It’s entirely possible what Philips were doing with their sound editing was inserting dramatic effect to counter-balance the neutrality of Bernstein’s dreamier approach to the score. But this filtering was often unevenly done. The Act III prelude, for example, is extremely lightweight, as is Isolde’s Liebestod which just sounds thin and strained - but, on the other hand, the endings to Act I and Act II are thundered out with such force they sound like sledgehammers by comparison. The sound on film is much more natural – though, of course, it does nothing to improve the deficiencies of the performance itself.

This is unquestionably an important document of Bernstein’s legacy as an opera conductor, though it’s inevitably a deeply flawed one. If there is one reason to buy the Blu-ray of this performance it’s that the shift in sound perspective gives us a quite different view of these concerts. Visually, it’s not especially interesting to look at – it’s as static as the performance is through its long stretches. I’ve always loved this Tristan for the playing of the Bavarian Radio Symphony Orchestra and that will never change – this is a near flawless orchestral performance, one of depth and sumptuousness that is unrivalled elsewhere, even by Karajan’s Berlin Philharmonic or Kleiber’s Dresden Staatskapelle. The impact they have on film is remarkable – and this is probably as close as Bernstein intended it to sound. It’s magnificent but frustrating in equal measure.

Marc Bridle