Probably our last Prom of the season, and a rare chance to see Rattle and the Berlin Phil, playing a challenging programme: Wagner's Prelude and Liebestod from Tristan und Isolde, and Messiaen's Turangalîla-Symphonie.

The Wagner piece is an interesting animal: 10 minutes of prelude to the opera, followed seamlessly by 8 minutes of arrangement of Isolde's closing aria. The opera is notable amongst musicologists for its use of a dissonant chord sequence at the very beginning (the "Tristan chord"), and for the way it used "suspended" chords: those in which the composer sets up your ear to expect the next chord in the sequence, and then leaves it hanging - to be satisfied later on in the piece. Traditionally, "later on" means some time within the next bar or two. In Tristan, Wagner sets up suspended chord sequences very early on which are only resolved at the end of the opera, so listening to the beginning and end bits and leaving out the several hours of music in the middle makes things considerably easier for the listener.

(By the way, anyone interested in hearing the Tristan chord can do so here.)

Wagner's music is very sensual, was considered very avant-garde for its day, and was played pleasantly enough by the Berlin Phil. But it was a mere amuse-guele compared to the all-out assault on the senses which was to follow after the interval.

The Turangalîla-Symphonie is an enormous work in every sense: 10 movements covering 78 minutes and a complicated plethora of styles, moods and textures: powerful brass fanfares, prestissimo string passages and old-time schmaltz tunes are interwoven with soft and ethereal sections featuring the glissando other-wordly sounds of the "ondes martenot" (a 1920s French attempt at what today would be called a synthesizer). Like the Wagner, it's firmly inspired by erotic love; unlike the Wagner, it is completely unrestrained. The Berlin Phil's performance was simply extraordinary, extracting the maximum of excitement and feeling from every passage. As well as fine performances from the soloists (pianist Pierre-Laurent Aimard and ondes player Tristan Murail), there was some highly virtuosic individual playing from the woodwind and brass players, and I've never heard percussion anything like this, with the bass drum reverberating like a rifle shot.

For the traditionalists, this is not "easy" music. There aren't simple tunes and harmonies to latch onto, and your ear is expected to follow an awful lot of different sounds and textures, often with several being played at the same time. I'm not a highly experienced listener to twentieth century music of this nature and was somewhat nervous about choosing this work, but to my astonishment, my attention hardly wandered in well over an hour of music, and I find myself definitely wanting more.

One hears a lot about the Berliners' "precise" playing, which is sometimes presented as implying a lack of emotion. That certainly wasn't the case here, and there's some basic physics going on which explains why. When a work gets its force from building to an explosive climax, if all the instruments play precisely together, their sound waves reinforce and the climax can be truly intense. If the orchestra lacks that precision - and all but the very best orchestras do - the sound waves interfere destructively and the result can vary from "not as exciting as you'd hoped" to downright murky. The Messiaen piece relies hugely on dynamic range for its impact, and the Berliners delivered it fully, with tutti to make you jump out of your seat, and soft passages to soothe and lull.

The audience did its best to demand an encore, but I suppose that after a piece of this scale, it was somewhat unreasonable to expect one. Still, people left the hall in a high emotional state, and I certainly left in awe of this magnificent orchestra, and of the scale and ambition of Messiaen's composition.

David Karlin 2nd September 2008