THE ALBUM -- Philip Glass's "Dance (Nos. 1 and 3)," Tomato (TOM-8029).; THE SHOW -- At the Pension Building Friday at 9.

The music of Philip Glass -- a combination of classical, avant-garde and rock forms using mainly synthesized and vocal sound -- is unquestionably an acquired taste. But some might consider the heady repetitive element of his work to be more tiresome than titillating.

"Dance (Nos. 1 and 3)," on the other hand, is a presumptuous little offering, but I think you will be amused by its verve. Whereas the highly-acclaimed "Einstein on the Beach" employed a broader range of motives, "Dance" spins its energy off one basic musical idea, further narrowing the listener's concentration.

The result is really several works in one: By focusing on a different voice with each listening, one comes into contact with the versatility that a deceptively isolated theme affords.

Unfortunately, it's precisely this approach which is likely to alienate much of Glass's audience, particularly those whose ideas about music are deeply rooted in western rhythm and scales. Glass would undoubtedly writhe at any comparison between himself and Jean Michel Jarre, but such a comparison is inevitable, given the similarity in their use of synthesized sound to create structural emphasis.

Where Jarre shows sensitivity to an audience's tolerance of musical unorthodoxy by allowing one idea to flow gently into another, or even to resolve itself, Glass seems bent on escaping resolution altogether, taking little turns here and there but never quite reaching the end of the road.

This isn't to say that the music is a dead end. But no matter how erudite or attuned his listeners are, some will find the constant building toward a culmination that never takes place a bit nymphomaniacal.

The trick to appreciating Glass's contribution to contemporary music -- which is considerable -- lies naturally enough in repeated listening. No idea that's new or stretches recognized boundaries seems attractive at first glance, and a deliberate flight into the face of the accepted isn't an exercise for the narrow-minded.

Although "Einstein" might be a better starting point for the uninitiated, "Dance" offers the beautifully understated choral work of the Philip Glass Ensemble, combined with the simplicity/complexity which has become Glass's hallmark -- all in a manner which, by meeting it halfway, could introduce us to new ways of thinking about music. There's always room for that.