When classical music is for adults only Music can do dangerous things to us. It can make us declare undying love, grab a sword and slaughter our foes, convert to a new vision of God. According to Homer's Odyssey, it can even make us leap into the sea and drown. Odysseus has to sail past the Isle of the Sirens, and has been warned that the Sirens" song will come upon him and his men unawares. It will drive them mad, and make them jump to their deaths. Odysseus tempts fate by ordering his men to lash him to the masthead, so he can hear the music, and to stop up their own ears with wax. Where do we find music of such dangerous power nowadays? Only in pop. At a rave, youth become as intoxicated as Odysseus's sailors would have been - except that the intoxicant is now the incessant beat of trance music. If we're looking for an apt classical parallel it's not the Sirens" song so much as the dances of the Bacchantes. These were so wild that a mother was quite capable of tearing off the head of her own son (as happens in Euripides's The Bacchae). Thank goodness such things don't go on at the Royal Festival Hall. Nothing symbolises the safe, repressed state of classical music quite so well as an orchestral concert, where the musicians are pinioned into formal gowns and penguin suits. But could it be that under its buttoned-up exterior classical music harbours all kinds of illicit passions, every bit as disturbing as those at a rave? That's the thought suggested by Exstatica, a concert from the BBC Concert Orchestra. "Ecstasy - exalted pleasure so intense rational thought and self-control gets lost - physically, sexually, spiritually," shouts the publicity. Below, in smaller letters, it says "this event contains explicit material and is suitable for audiences aged 16+," which must be a first for a BBC orchestra concert. Take a closer look, and it becomes clear that there's more than one kind of ecstasy going on here. On one side there's Michael Torke's Ecstatic Orange and an orchestral arrangement of the Pet Shop Boys" hit I Wouldn't Normally Do This Kind of Thing. These will blast us with the kind of unruly rhythmic energy that's rare in an orchestral concert. The first time it was heard in classical music, at the 1913 premiere of The Rite of Spring, the shock made people lose their heads. One listener was seen pounding out the music's rhythms on the bald pate of the listener in front of him. A full-blown riot soon ensued. On the other side, there's Michael Nyman's setting of some very saucy poetry by Renaissance poet Pietro Aretino (thus that parental guidance warning), and Schoenberg's Transfigured Night. These point to a different sort of ecstasy, much more typical of classical music, which has to do with eroticism rather than wild, abandoned dance. It's engendered by waves of harmonic motion, which generate tension and then release it. Italian Baroque composers were especially good at this. Mozart was, too. Beethoven, who was somewhat prudish, was less so. In the Romantic period, composers screwed this effect up by several notches. In Schoenberg's piece, the tension is raised to fever pitch. But the greatest master of this aural eroticism was Wagner, a composer who's strangely absent from this concert. The word "orgasmic" is nowhere more aptly applied than to his Tristan and Isolde. Researchers have shown that the surging waves of the opera's Liebestod (Love Death) mirror the patterns of the female orgasm (you wonder quite how they tested this hypothesis). So, two sorts of ecstasy, governed - one hopes - by classical decorum. But can we be sure that the audience won't be driven mad, Odysseus-like, on Monday evening? Remember Tolstoy's Kreutzer Sonata, where a respectable bourgeois lady is driven into the arms of her lover by the passionate strains of Beethoven's Kreutzer sonata. Remember Emma Bovary, who got a fit of the vapours while at the opera. Remember the man at The Rite of Spring's premiere. Perhaps the management should have the constabulary and some smelling-salts at the ready, just in case.