WHEN minimalist music first emerged about 25 years ago, courtesy of such ornery new composers as Philip Glass and Steve Reich, it generated a lot of controversy.
Some listeners were entranced by its insistent melodies, repetitive rhythms, and crystal-clear harmonies. Others found it a nonstop bore, no more engaging than the warm-up pieces in a grade-school exercise book. Still others found it an interesting novelty with diminishing appeal over the long run.
Of these positions, the most dismissive has turned out to be the least defensible - if only because minimalism still prompts debate and discussion a quarter-century after its arrival on the scene.
Now a batch of fresh releases on the Elektra Nonesuch label, which recently added Glass to its growing roster of innovative talents, is providing the grist for a mid-1990s reassessment of his career, and of the minimalist style itself.
All newly recorded by Glass and his associates, the works on these compact discs range from experimental compositions of the late '60s to some of his latest pieces. As a whole, they offer compelling evidence that minimalism remains a vigorous and viable form. They also indicate that its earlier phases are a lot more exciting than its current manifestations, however, and that the style has evolved so much that the term ``minimalism'' seems less adequate than ever.
As a listener with a longtime interest in minimalism, I've formed my own set of preferences vis-a-vis the strategies Glass and others have employed to keep their music from settling into stagnant and self-plagiarizing patterns - always a danger with a style that prides itself on a carefully limited vocabulary of musical resources.
Glass has brought a sense of diversity and growth to his work by gradually extending his harmonic and melodic range, and by switching from a heavy emphasis on small-ensemble pieces (written for his own group of amplified keyboards and woodwinds) to a vigorous engagement with full orchestral forces.
Ironically, the new Elektra Nonesuch releases confirm my feeling that Glass's work is more vital, imaginative, and just plain riveting in the comparatively ``pure'' form it took in the initial years of his career.
This doesn't mean his recent works are dull or without merit, or that his early pieces are uniformly great. But there's little doubt that his intensity and inventiveness shine most brightly in the pieces that really are minimal, rather than the more complex compositions that draw on minimalist mannerisms while seeking to transcend them at the same time.
If there's a single disc that best illustrates the richness of early minimalism, it's the new untitled collection of four seminal pieces, not available on CD until now.
It begins with a late-'60s piece called ``Two Pages,'' an utterly uncompromising organ-and- piano work that spins a single phrase into a quarter-hour of expanding and contracting sound that's as spellbinding as it is rigorous.
This is followed by two 1969 compositions: ``Contrary Motion,'' an essay in ``open form'' counterpoint that adds a sparse but insinuating harmonic dimension to the composer's arsenal of effects, and ``Music in Fifths,'' which carries the style another step forward by hewing to an internally logical structure with a clear beginning, middle, and end. The disc concludes with ``Music in Similar Motion,'' still more sophisticated with its precisely wrought progression of austere polyphonic lines.
An interesting byway in Glass's development is represented by ``Music With Changing Parts,'' released on its own disc and dating from the exciting early-'70s phase of Glass's career.
During performances by his ensemble in this period, Glass had noticed that the repetitive lines played by the keyboard instruments clustered into unexpected patterns with their own melodic chacteristics; taking advantage of this, he wrote a piece that allowed wind instruments and voices to choose any such pattern that sounded appealing and reinforce it through imitation as the performance proceeded.
This brings an element of improvisation to the work - very rare in minimalist music - and gives the composition an enveloping warmth that smacks more of ``new age'' prettiness than the crisp exactitude of full-fledged minimalism.
It's a likable piece, though, and might be a good starting point for newcomers to the genre. It also marks an interesting footnote in minimalist history, since it was composed around the same time as Reich's great compositions ``Drumming'' and ``Music for 18 Musicians,'' which use similar devices of reinforced patterns and breath-length phrases.
The later works in the Elektra Nonesuch collection are less enticing. Scored for a percussion-enhanced version of Glass's ensemble and a conventional array of voices, the cycle of poem-songs called ``Hydrogen Jukebox'' sets verses by Allen Ginsberg to music that lacks the sonic punch of Glass at his best, despite some haunting moments and the benefit of Ginsberg's inimitable recitations at key points along the way.
The weakest of the discs is ``Anima Mundi,'' a movie score that reveals Glass's frequent tendency to fall into uninspired atmospherics when composing for orchestra rather than a smaller, more intimate group.
Not surprisingly, the most triumphant of all the Glass albums released so far by Elektra Nonesuch is the new recording of ``Einstein on the Beach,'' an opera written in collaboration with director Robert Wilson and ranking with this century's towering musical achievements.
Superbly played by the Philip Glass Ensemble and violinist Gregory Fulkerson, with a skilled chorus and a quartet of sonorous speakers, the new rendition is a bit quicker and cooler than the earlier version released on the Tomato and CBS Masterworks labels. On the minus side, some of the new recording's spoken portions are a bit less resonant than those of the previous edition; on the plus side, it provides 30 more minutes of the complete score than its predecessor, although its 190-minute length (on three discs) still falls short of the opera's full 4-1/2-hour splendor.
All told, it's a thrilling new addition to the ever-growing library of first-rate minimalist recordings - and a forceful reminder that the greatest of these works are so imposing and expansive that the ``minimalist'' label hardly begins to describe them.
* Coming soon from Elektra Nonesuch is a digital three-disc recording of Glass's lengthy 1974 piece ``Music in Twelve Parts,'' played by the Glass ensemble. Steve Reich and John Adams are other composers associated with the minimalist style who release their works on this label.