IN A CAREER brimming with persnal satisfactions and public triumphs, what most intrigued composer Richard Rodgers? "The unexpected moments," he once said in an interview with Richard L. Coe, "like driving up the parkway late at night, all alone, and hearing a tune that came from my head. It comes as such a surprise, a shock almost, and it's the most profound feeling I've ever had in my life. Aren't I lucky that though I never know when it will happen, it's recurred again and again?"

So many times -- and so splendidly. From picking out tunes on a piano at the age of 4 until his death Sunday night in New York City at the age of 77, Richard Rodgers filled the air with memorable music. From dozens of Broadway smash hits came tunes that will be sung, whistled and hummed as long as there are hearts to lift and toes to tap.

Not only do the melodies linger on, but so does the new and distinctly American form of theater produced by Mr. Rodgers' collaboration with lyricists Larry Hart and Oscar Hammerstein II. It was no mere extension of the European operetta style; most musical comedy of the 1920s was, as longtime Rodgers friend and publisher Albert Sirmay put it, "strictly a boy-gets-girl, moon-June sort of show. If the libretto was a rigid affair, so was the song pattern. . . . The story started, then stopped for a song." But Mr. Rodgers and his partners integrated song and plot, and eventually chose the themes for their musical works.

So it was that a grand celebration of pioneer America -- "Oklahoma!" -- captivated young and old first in this country and then around the world. With astounding speed, Mr. Rodgers continued to turn them out, composing on luncheon menus, in his head, in taxis or hotel lobbies. He wrote the score for "Oklahoma!" in six days, the melody for "Bali Ha'i" in roughly 10 minutes, and another that took slightly longer: "Victory at Sea," said to be the longest symphonic score ever composed, lasting 13 hours.

Mr. Rodgers said he had no favorites among his own tunes, though his favorite show was "Carousel"; it included "You'll Never Walk Alone," which, he noted, "is played at both weddings and funerals and occasionally in between." He would say that "they're all like children, and you love them each for something else. . . . Nothing matches the exhilaration of conceiving and creating with others something that has no purpose other than to give people pleasure."

Nothing -- except the pleasure itself, from an incredibly rich and lasting legacy.