"It's high time that we woke up again to the fact that the `dance round the golden calf' has been going on long enough," he says emphatically. "And we really have got to look at ourselves, and ask what the hell we are actually doing here." So, can music really help us to reclaim our spiritual values? "Certainly, music has a great deal to offer in that respect," insists Davis, "and we treasure the great pieces because of that spirituality."
Bruckner's symphonic world is something of a spiritual apocalypse. Think of the Eighth Symphony's cataclysmic first movement. "And the last movement of the Sixth," adds Davis, "the work we'll be playing next week. It's the world under threat, or Bruckner's soul under threat from the Inquisition. A terrible march is going on there, with blaring trumpets, threatening interruptions from the brass and terrifying squeals on the other instruments. It is the most extraordinary piece." Is that, then, why he chose that particular symphony to open the season? "To be honest, I chose the Sixth Symphony because it is the one that doesn't really get `mentioned in dispatches'; it's usually the Fourth, Fifth or Seventh - but the Sixth is a particularly beautiful work. In some respects, it is really a pastoral symphony. The orchestral colourings are remarkable, and there seems to be no reason why the piece should stop - which is the sort of feeling you often have with great music."
Davis conducted Bruckner's Seventh Symphony and F minor Mass during his stint as chief conductor of the Bavarian Radio Symphony Orchestra in Munich. His readings - and recordings - were widely praised, especially abroad, but was that the limit of his Brucknerian repertoire at the time? "Yes. It wasn't until I came to the LSO that I learnt another four symphonies. It was, above all, an adventure in coping with great blocks of sound. You know how Bruckner puts them side by side and doesn't really think about joining them up? Brahms does that, too." So there is a marked difference between the Munich and London orchestras' response to Bruckner? "Yes. There's a tremendous difference," confesses Sir Colin, "because the Bavarians have played Bruckner ever since they can remember. Their first conductor was Eugen Jochum, who did loads of Bruckner, and then Rafael Kubeuk - who was the orchestra's chief conductor before me - was a great Bruckner conductor." Initial suspicions soon gave way to approval. "When I came along, as an Englishman, they naturally thought, `he doesn't know anything about Bruckner'. But the advantage of playing Bruckner with the LSO is that the orchestra doesn't really have the music in their bones either, so you start off on an equal footing, discovering how a piece could go. And it can go in so many ways; I can't think that the performances of other composers vary quite as much as they do with Bruckner."
Bruckner is still misconceived as heavy, marmoreal, monotonous, a sort of annexe to the Wagnerian edifice, but Davis intends to help combat these common misconceptions. "And I feel very strongly about it," he insists. "The aspect of relative tempo is enormously important, and by that I mean that even the people who love Bruckner's music take passages that they think are rather boring, change the tempo and hurry the music along until they come to another glade in the forest where they can relax and enjoy themselves. I don't think that works. I don't think that the logic of the pieces comes through in that way. You get wonderful episodes in these performances, and then whole passages that are treated as transitional. Admittedly, it is very difficult because not all the material really goes into one tempo - and tempo variation in Bruckner is vital. You should allow each episode to blossom rather than hurrying past the landscape just because the flowers aren't open."
As to present performers, how do the players adapt to the epic timescale of Bruckner's music?
"You must above all have a sense of musical structure, of order. That is reflected in what our orchestra tries to do. There are all those disparate characters sitting out there. We don't know who they are; but in order to sit and play a Bruckner symphony, they have to sacrifice their egos - because if they bring their egos on to the platform, they will immediately wreck what is going on. They contribute to something that is much greater than themselves, and produce this vision of order. It costs people a very great deal to do that, but I think we demonstrate that it is possible."
Later on in the season, Sir Colin conducts the major orchestral works of another great late-Romantic, our own Sir Edward Elgar. Parallels with Bruckner centre mainly on a common facility for melodic invention. "If we listen to the First Symphony of Elgar and the slow movement of Bruckner's Sixth Symphony, we can't help but notice that both composers have a fantastic way of spinning melodies, something that goes all the way back to Gluck and Berlioz, but not in that incredibly solemn way. The slow movement of Bruckner's Sixth is really a slow march; in fact, it becomes a funeral march, and Elgar's slow marches are always effective. I think in particular of the slow movement of the Second Symphony, which is one of the most wonderful pieces I know."
Elgar and Bruckner were both epic symphonists, unlike Mozart, the other composer on Wednesday's programme. Sir Colin's Mozart performances are by now legendary, both in the opera pit and in the concert hall. But has Salzburg's greatest son lost any of his power to inspire, to humble? "Mozart is the god of love," Davis says decisively. "He tells us that we're so ridiculous, and that the simplest thing is to forgive one another, laugh at one another and love one another, and go out and have a good meal!" But surely there is a darker side to Mozart, a minor-key sense of unrest? "OK. Then he's accused of trying to break up the universe because of Don Giovanni, and I think that there he is misunderstood. Mozart despised Don Giovanni because the Don has no inner life of any kind. He hasn't anything to say. He has no proper aria because he doesn't exist as a person; he's just a machine for disrupting things. And so perhaps Mozart wrote his greatest music just to send this chap down, because he was so intolerable. He also demonstrates, in the same work, the temptation of following stars: Don Giovanni is a star; he's a pop star, a football freak."
But not all crowd-pleasers are "mere" stars. Earlier this year, the composer Anthony Payne stole the nation's hearts with his sensitive elaboration on Elgar's sketches for a Third Symphony. Davis will include the new "Elgar Third" in his forthcoming Elgar series. "Payne has come up with a most extraordinary piece of work," he says. "Only the second movement still puzzles me. I'm not quite sure whether I've found my way into that yet, but the first movement has a genuine Elgarian swagger." That was in July, so by now, Davis may have fathomed the mysteries of that elusive second movement.
As to the more general questions about New Music and whether or not the past has an exclusive claim on musical greatness, Davis returns to the perennial ideas of form, order, a centred "mean". "Since the collapse of the Classical system of composition, we've seen various alternatives," he says, "but none of them has survived. There's too much music just being composed. It will take a great spiritual revival, or a need to write what we would call `great' music, to draw all this new experience into a centre where it can be organised by some exceptional musician. Then they will write a great piece and we will recognise it as such. It has been so centrifugal, the whole thing, hasn't it? People whirling around, getting further and further apart. It has got to come back, congeal - and maybe then we will find our souls again."
Sir Colin Davis conducts the opening concerts in the London Symphony Orchestra season on 23 and 24 September at the Barbican (0171-638 8891)