Merce Cunningham makes you see dance as if for the first time

By all normal standards, Merce Cunningham is the grand old man of modern dance - this year marks the 30th anniversary of his troupe. But the comfy connotation of this phrase is as far from the Cunningham experience as one can go. Having just seen the Merce Cunningham Dance Company at the City Center, where it performs through March 27 before embarking on a European tour, I was struck again by the astringent, clear-minded qualities of Cunningham's choreography and dancers.

Seeing his works is like going back to the source, like seeing dance not so much for the first time as for the cleanest time. Although it's foolhardy to wrap a person of Cunningham's magnitude in tidy generalizations, I think it's true to say that the longer he's around, the purer his dances become.

These dances deal with essences, and the more they shave away unessential decoration, the more poise and confidence they assert. In a sense, the content of Cunningham's dances grows younger while their attitude about their subject matures. That's about the best possible kind of development, as Sophocles implied in his trilogy about Oedipus.

Since this little preamble can hardly do justice to the stunning beauty of Cunningham's ''Quartet,'' which receives its New York premiere this season, suffice it to say that it was occasioned by ''Quartet.'' All ''Quartet'' is, really, is an exploration of changes that occur when four people dance together. The changes are small and subtle, and all the more enthralling because of it.

''Quartet'' contrasts motion that passes from person to person in succession with motion that seems to arise in a collective voice. One idea leads to another , but sometimes there is spontaneous combustion. Part of ''Quartet's'' excitement is that it enables the viewer to sense inside himself the differences between evolutionary growth and sharp mutation.

The relationship between the dancers is also in flux. Sometimes they move in conventional groupings, and no matter what the particular formation - as couples or as soloist against ensemble - they're a group. The dance has the appearance of symmetry. But often it pries loose from pattern. It floats by in fragmentary images, the focus dramatically shifts to a corner of the stage, and while four people might happen to be inhabiting the same space, they could be 400 or 1. These moments of disintegration are rare, but they serve to make the dance pleasurably tense and in delicate balance.

''Quartet'' would hold its balance without the linchpin Cunningham has provided. But the linchpin does add much dramatic coloration. It's Cunningham himself, presiding over the four dancers as a kind of Prospero. Standing apart from the others, he seems both to signal the course of the action and respond to it as a chorus. You can't tell if his presence is entirely benign or indifferent , but he's definitely a power.

That this dance for five is called ''Quartet'' is accurate in a bare-bones kind of way. The title is also a knowing little joke, for what would the quartet do without the fifth wheel?