The Modern Jazz Quartet is so subtle that it has not even bothered to pin down its beginnings to anything so crude as an exact date. For a couple of years , it seems, these four fellows from Dizzy Gillespie's band were just sort of noodling around after hours. Their history starts in the middle of a measure, as it were, like one of those sudden notes Percy Heath plucks from his bass.
This much is fixed and certain. Thirty years ago the Modern Jazz Quartet made the first recordings to give its name public prominence. And so (to the accompaniment, please, of one of those little toy-drum rolls from Connie Kay) we wish a happy birthday - any day now - to the nearest thing to a chamber music ensemble that jazz has ever known.
Thirty years ago a lot of jazz was shrill with high-note trumpets - frantic with double-time saxophones. Bebop had become the fashion, and at its least-inspired moments bebop simplified itself into a formula. Success equaled the maximum number of notes played at the highest speed and the loudest volume, while maintaining greatest distance from the melody.
John Lewis, the pianist of the Modern Jazz Quartet, who refers to himself as its ''musical director,'' has stated his manifesto: ''I think that the audience for jazz can be widened if we strengthen our work with structure. The improvised and written sections should not take on too much complexity - the total effect must be within the mind's ability to appreciate.''
So, while bop musicians in wildly padded shoulders and cra-a-azy hats were blasting nightclub patrons with their overpowering originality (they hoped!), the MJQ, in black ties, cultivated the concert hall scene, distinguishing itself as the first jazz ensemble to become famous for being subdued.
With all the dignity of a string quartet - and not a lot more dynamics - the Modern Jazz Quartet substantially redefined the possibilities of jazz. Even after 30 years one can feel a delicious little surprise, watching John Lewis hunch over his keyboard to perform ''Meditational Excursions'' while Percy Heath , tall and aristocratic, bends over his bass as if it were his partner in a minuet.
Connie Kay, rather looking like a scholar on sabbatical, hardly seems a drummer at all in the old bam-wham tradition as he fusses delicately with chimes , wood-blocks, and whispery cymbals.
Even Milt Jackson, who, by default, must be regarded as the funky voice in the group, gentles his vibes with one ear cocked, as if they possess all the lovely frailty of a harpsichord. Which, in fact, John Lewis has been known to play.
This is jazz? These MJQ classics with titles like ''La Ronde'' and ''The Queen's Fancy'' and ''Two Lyric Pieces: Pierrot and Columbine''?
Isn't jazz supposed to be spontaneous, random, free-form? Here everything is as nicely taut as a Bach fugue.
Isn't jazz supposed to exist for the benefit of the soloist? Here everything fits together for one common effect almost too neatly.
Isn't jazz supposed to be a matter of drive? Here everything seems to be a matter of touch, as if all four were listening to a ballade by Chopin. Can anything this gentle, this urbane, this civilized, be jazz?
The above questions are full of common half-truths about the nature of jazz. But even if they were valid, listen to John Lewis on his own composition, ''Django'' - as toe-tapping as Count Basie. Or try Milt Jackson on ''Bluesology'' - as salty and biting as the blues can get.
John Lewis played with Charlie Parker as well as Dizzy Gillespie. These robust roots are worth recalling. For the MJQ has not refined the life out of jazz by adding luster and elegance. Rather, it has done on a small scale something of what Duke Ellington did with a full orchestra - put a polish on all that vigor.
What a pleasure it is in art - in any human enterprise - to find the virtues of wit, intelligence, and sensibility celebrated! More than we know, they redeem the brutish emphasis on will and force in the world about them. Rubinstein, Casals, Segovia, have commanded these virtues well into their ninth decade. Is it too much to ask for another 30 years - more or less exactly - from the Modern Jazz Quartet?