After three years of work, Philip Glass has finally completed his ‘Music in 12 Parts,’ and it is a major accomplishment. The work, which was presented in its entirety for the first time at Town Hall on June 1, contains four hours of music altogether, and there is no padding. It is rather complex music, extremely rich in ideas, but also strong in its direct emotional impact. And the ensemble of Jon Gibson, Dickie Landry, Richard Peck, Bob Telson, Joan LaBarbara, and Glass sailed through the long taxing evening with apparent ease.

I have already written about the rich blended sound Glass gets with electric organs, amplified winds, and an occasional female voice, and about the static or minimal or hypnotic style of his music, which ripples along on endless eighth notes. But I have never emphasized the complexity of his work, because only now, having heard all 12 parts of this piece in a single evening, can I see the degree of inventiveness and the variety of the intricate techniques which he has found within the severe restrictions of his style.

Only toward the end of Part V did I ever lose interest in what was going on, and even there the problem could have been my inability to latch onto things, rather than any lack of ideas on the composer’s part. In general, the music constantly uncovered new possibilities and constantly challenged my ear and brain. And it never became dull or repetitious, despite all the repetition.

Sometimes the interest lies in gradual fluctuations between modes, like a shift between a kind of major key sound and a kind of minor key sound.

Sometimes the focus is on polyrhythms, with little contests between, say, the three four figures and the six eight figures.

Sometimes the music is simply unison melodies, but with small variations in individual instruments.

Sometimes unison melodies become parallel fifths, often so subtly that one hardly realizes the shift is going on.

In some sections, at the whim of the performer, sustained tones creep in and out, having strange effects on the moving parts.

Sometimes syncopated rhythms simply wind around each other in cycles. But if the cycles are repeated 15 or 20 times, as they often are, it is only because it actually takes the listener about that long to figure out what is going on.

Frequently figures repeat over and over, gradually adding notes and becoming longer, or gradually omitting notes and becoming shorter.

In the more recent of the 12 parts, the music sometimes alternates between two kinds of material. Both sets of material go through independent variations as the antiphonal music shifts back and forth.

Another technique common in the recent parts is the sudden modulation. At unexpected moments, the music suddenly pops into a new key, making it hard to remember where you just were or to figure out how you got where you now are.

There are constant fascinations, and they always happen on a level of subtlety where you can’t quite figure out what the hell is going on. Glass may be avant-garde in many respects, but he apparently respects the age-old art of concealing art as much as any past master.

One of the pleasures of Glass’s music is his joyous optimistic tone. No gnashing dissonances, no eerie sounds, no melancholy moments, no downs. It just keeps chugging away toward some ultimate high. I’m not sure that’s necessarily a good thing, as most of the music which has lasted in our culture is music which contains liberal doses of the bitter along with the sweet. But I’m certainly not complaining. A little musical optimism is a refreshing contrast to the dark expressionistic shadows of Schoenberg, Berg, and Bartok, which still hang over so much contemporary music.

As I was sitting in Town Hall that night I couldn’t help thinking of a letter which had been in the Voice that week. Someone named Matthew Paris had written about how he usually stayed home and listened to records instead of going out to concerts, because he felt that concerts seldom offered anything he could not get on records. I doubt that Paris bothered to attend Glass’s concert, but if he had, the experience might well have turned his head around.

If and when ‘Music in 12 Parts’ does come out on records, I imagine it will be a six-record album, and it will probably come to five or six times the price of a ticket to this concert. And even with a relatively luxurious home stereo set-up, Paris will never be able to reproduce this music as vividly as the live performers can produce it on their own superb sound system.

Like a lot of music being created these days, the effectiveness of Glass’s subtle textures depends quite a bit on hearing them at the right volume and with just the right balance of voices. Even Kurt Munkacsi, the group’s sound man, can’t always get things exactly right for all parts of a hall, but he comes a lot closer than anybody’s home stereo system will.