If not the 'essential' Philip Glass (admirers and detractors alike could make a meal of the concept of 'inessential' Glass) this is certainly the essence of him, usefully indicating to the detractors that in fact he hasn't simply been writing the same piece over and over again these 30 years. His music doesn't chug quite so much as it did, its sound has grown more dulcet, its lines longer. I still find it very hard to listen to. Different types of music have different functions, demand more or less of our attention. Less than 50 per cent in the case of dance music, say, where you're expected to devote some of your attention to what your feet are doing, some to your partner; you're also allowed to talk. In the case of some popular music it's well under 50 per cent: the appearance and personality of the singer or group and the social or fashion statement they and you are making are both at least as important as the music.
Glass's music does not respond to the sort of 100 per cent attention that we're accustomed to giving to 'serious' music: there isn't enough there to engage the whole mind. The solo piano piece Metamorphosis Four is typical: a two-note oscillation and a simple harmonic sequence (which sounds rather like part of the accompaniment to a Schubert song) are combined; after a while the oscillation turns into a running figure; seven minutes later the music stops. Tolerable as an accompaniment to some other activity, but in the absence of any surprise, conflict, tension or expectation denied it isn't so much minimalist music as incomplete music, music with a vital element lacking. In some of the operatic pieces a longer melodic line will keep you guessing for a second or two about where it's going, but only for a second or two. In the number called ''Protest'' from Satyagraha a repeating chaconne-like ostinato attracts the attention; but the function of a chaconne bass is to support and anchor inventive fantasy, and fantasy is absent here. It is mechanistic, cold, undemanding un-music, and its widespread popularity (Glass is said to be the most commercially successful of all living composers) is rather depressing. It was necessary, of course, to protest against the arcane, unapproachable complexities of hard-line post-serialism, but dozens of composers more accomplished than Glass did so without retreating to such a frozen, eventless wasteland. The performances all have the composer's imprimatur; the recordings are clean and forward.'