Olivier Messiaen

But the thought is one that Messiaen must have applied to almost everything he produced during his long career. He was a master craftsman, a painstaking musical inventor whose every note resonated with beauty. Yet his music somehow reached beyond its own limits, toward an essence vaster and infinitely more sublime than any that might be contained in a mere work of art. However polished and perfected his music sounded to others, to Messiaen it could never be more than a tentative step in the right direction. Messiaen seemed to know his place in the world; for him, to compose was to express not genius but humility.

Messiaen died last month at age 83, and the niche he occupied will doubtless remain empty for a long, long time. Although he had many students, he had no real emulators. Indeed, with Messiaen's passing, Western culture lost an artist of the rarest sort; in recent decades Messiaen scored triumph after triumph in concert halls around the world, and he did it with music that is not only strikingly modern but - in and of itself - profoundly sacred.

As a successful composer of sacred music in a boldly secular age, Messiaen fits peculiarly into a meandering lineage that is traceable to the years when literacy first began to shed its light on the Dark Ages.

In the beginning, presumably, sacred music was far removed from its secular counterpart. The latter was never set to parchment or paper, but historians - trusting more on their knowledge of human nature than on actual evidence - guess that it was relatively simple song-and-dance material. Sacred music from as early as the seventh and eighth centuries, on the other hand, exists in a multitude of notations, and the bulk of it that has been deciphered appears to be rhythmically fluid and melodically austere. Whereas secular medieval music existed to amuse an audience, Gregorian chant - as the main body of sacred music later came to be known - served a higher purpose; it was aimed not at listeners but at participants, for it was a public manifestation of otherwise intimate prayer.

But as the centuries wore on - as musical notation became codified, as musical composition became more and more a professional's activity - there was a gradual blending of sacred and secular styles. A composer in the 14th century would likely have been trained in a monastery, but if he were talented his patrons would have included dukes as well as bishops. Similarly, a successful composer in the High Renaissance, although he might have stayed a layman, would have been as busy writing masses as madrigals. Italians in the early Baroque period made a distinction between musica da chiesa and musica da camera, but the distinction was largely nominal; although certain instruments and rhythmic patterns were specific to one venue or the other, the basic content of music for the church and music for the chamber was essentially the same.

Essentially the same, too, are the ingredients of sacred and secular music in the standard repertoire. Technically speaking, there is no difference at all between Bach's subtly erotic ''Wedding Cantata'' and his cantatas on Biblical themes, between Beethoven's profoundly Christian ''Missa Solemnis'' and the joyously humanistic finale of his ninth symphony, between any of Verdi's operas and the ''Requiem'' that the St. Louis Symphony and Chorus are presenting in Powell Hall this weekend. There is no difference because these composers, like their predecessors for hundreds of years, spoke only a single musical language; long before Vatican II, in the world of sacred music everything was in the vernacular.

It was into the French version of this tradition that Messiaen was born, in Avignon, on Dec. 10, 1908. There was nothing in his childhood that, on first glance, suggests his future course. His father was a professor of English at the local high school, and his mother - Cecile Sauvage - was a poet. Cultured but not at all religious, the parents naturally steered their son toward their own household gods. By the time he was 8, Messiaen had read the complete works of Shakespeare and most of Tennyson. What he found especially appealing in these authors, Messiaen told interviewer Claude Samuel in 1967, was their treatment of fantastic themes. And it was for the same reason that, early on, he was attracted to the operas of Wagner, Gluck and Berlioz. For Messiaen, Shakespeare's ''Tempest'' and Berlioz's ''Damnation of Faust'' were ''super-fairy tales'' that made the usual juvenile fare seem like mere kids' stuff.

His first efforts at composition were piano pieces based on his favorite literary themes; for the young Messiaen, music was a medium whose prime goal was the telling of exotic stories . Considering his strong theatrical bent, it is interesting that not until he was almost 70 did Messiaen give thought to writing an opera. Viewed from another angle, however, the ambitious ''St. Francis of Assisi'' - started in 1975 and premiered in Paris in 1983 - stands as a logical near-completion of a cycle of compositions that began soon after Messiaen reached his maturity.

It was when his father was off fighting in World War I that Messiaen, quite on his own, discovered the power of religious faith. In the lore of Catholicism, it seems, he found imagery far richer than that contained in any of the ''super-fairytales''; here was ''the marvelous multiplied a hundredfold, a thousandfold,'' he told Claude Samuel, a source of inspiration irresistible because it was ''something true.'' And he found more than that - not just a beacon that would guide his activity but an answer, ineffable yet satisfying, to all his questions about the meaning of life.

Had Messiaen been born a millennium earlier, he probably would have entered a monastery and devoted the rest of his days to celebrating God through the composition of chant. But he was born early in the 20th century, on the eve of musical modernism. Intrigued more by the new than by the old in music, he enrolled at age 11 at the Paris Conservatory. Messiaen learned quickly all that his teachers had to offer, then, as a strong-willed young adult who defiantly opted to avoid the vernacular, he plunged deep into foreign territory. He explored, among other things, the rhythmic structures of various non-Western musics and the melodic intricacies of birdsong. He invented scales (the so-called modes of limited transposition), systematically organizing the multitude of chords their notes could produce.

And he composed, intensely if not prolifically. As did his hero, Debussy, Messiaen twice lost his bid for the Conservatory's prestigious Prix de Rome; in the process, he learned the value of following the dictates of his own musical conscience. Messiaen's music, from the late '20s on, is remarkable for its shimmery tone-colors and its seemingly weightless harmonies. But it is even more remarkable for its temporal elements. Except for the deliberate imitations of birdcalls, there is hardly a rhythm in Messiaen's output that is not rooted solidly in some mathematical scheme. Yet none of it seems formulaic, or sounds repetitious, or feels in any way earth-bound. While the durations of Messiaen's notes are necessarily limited, their carefully ordered combinations nevertheless have a timeless quality.

The sentence quoted at the beginning of this article comes from the preface to a piece written early in World War II while the composer was held captive in a Nazi prisoner-of-camp, a chamber music essay custom-made for Messiaen and three fellow POWs, a rapturous work based on the Book of Revelations and called ''Quartet for the End of Time.'' But almost all of Messiaen's music, from before the war and after, focuses similarly on the theme of eternity. A simple browse through Messiaen's titles - ''The Ascension,'' ''Visions of the Amen,'' ''The Transfiguration of Our Lord Jesus Christ,'' ''Three Liturgies on the Divine Presence,'' ''Et exspecto resurrectionem mortuorum,'' ''Colors of the Celestial City,'' ''Meditations on the Mystery of the Holy Trinity,'' ''From the Canyons to the Stars'' - reveals their extra-musical gist. But it requires the attentive, uninterrupted experience of these pieces even to begin to grasp their real content.

Although Messiaen was a devout church-goer who throughout his life used music to illustrate a specific orthodoxy, the compositions themselves seem to transcend any single system of belief. They are not so much religious as spiritual, not so much Roman Catholic as just plain catholic. To Messiaen they may have amounted to mere ''childish stammering,'' yet they stammer with uncommon eloquence, and they do serve to put listeners in mind of a subject whose grandeur, indeed, is overwhelming.