IT SEEMS unlikely that Ludwig van Beethoven ever even heard of Thanksgiving, though chronlogically there is no reason why not. And yet, if you consider it, he created an absolutely matchless contribution to the spirit of this curiously American rite that, for some of us, happens to be our most cherished holiday.

An incredible volume of music has been written for Christmas (Handel's "Messiah," for instance). Likewise, for Easter (Handel's "Messiah" again, for instance). Likewise, too, for Yom Kippur (the choral works of Ernest Bloch).

But nobody has consciously written at that esthetic level for Thanksgiving, perhaps because it is a secular occasion.

No matter. The great Thanksgiving work has been written. It is Beethoven's setting of Johann Christoph Friedrich von Schiller's idealistic poem called the "Ode to Joy," an expression of the high revolutionary hopes for a new age of universal fraternity so characteristic of the era in which the composer grew up.

He chose the "Ode" as the subject of that vast vocal panoply that concludes the last of his nine symphonies. The music is an utterly original creation -- structurally, expressively and in almost every other way, stunning in its boldness. The odds were that it wouldn't work, this lengthy movement in which Beethoven leaps from the restraints of sonata and rondo forms and creates something for orchestra, chorus and four soloists, something that is just Beethoven.

It is an exultant outburst -- explosion is almost the word -- of optimism and commitment and love from a miserable recluse with fewer than three years to live. He was a sad figure even though by then he was widely established as the world's most eminent composer. Here we have a giant among men, broken by disease, coming to terms with those remaining aspects of human experience that made him still grateful to be among the living. What could more eloquently express the meaning of Thanksgiving?

What was going through Beethoven's mind when he devised this extraordinary creation? He was obviously trying to outdo himself, something he had been doing strenuously throughout his career. And he clearly felt the footsteps of mortality close behind him, so he probably felt that it was now or never.

There was a little bit of a precedent in his works for this movement--a dry run, as it were. It came 16 years earlier and it was the Fantasy in C minor for pianoforte, chorus and orchestra, Op. 80. This writer regards it as one of the few mediocre works Beethoven ever produced, but at least it gave him some exercise in the huge combination of forces, minus the piano, that he would need in the "Ode."

To these ears the finale of the Ninth--described in the simplest terms--falls into four dramatic segments. First there is that extraordinary outburst of discord in the first seven bars, as if to wipe away the hour or so of masterful music that has come before. Then the movement leads into what seems to be a quest for a musical theme, as if the whole world that came before it has been shattered. With prose-like passages of what in opera are called recitatives, a fragment of a theme from each earlier movement is tested and found wanting. There are hints of the coming choral theme -- of reconciliation -- in the winds and then finally it comes -- just about as directly as could be conceived, in unison in the lower strings, very softly; this is the foundation upon which this entire majestic musical edifice is going to be erected.

It gathers power until all the giant forces are involved. The bass has the first words, with this exhortation: "O freunde, nicht diese To ne" ("O brothers, these sad tones no longer").

The music surges forward. Within a few minutes there is daring fortissimo cadence, and the music stops for a moment, and we move into a next stage, a series of variations that just keeps escalating in excitement, including a breathtaking double fugue that overwhelms the listeners emotionally and often overwhelms the players technically. Then begins a resolution, a long series of the most eloquent episodes, complex in music as well as text. They keep dwelling on the words, "Alle Menschen" ("All Mankind"). Finally the symphony ends in an absolute frenzy of a coda, for the orchestra alone, because no soloists or chorus could conceivably keep up with that pace.

What a piece of music!

Just to think that Beethoven, even though he conducted the first performance, never heard it.

What a man!