"I used to dread it when we would play Pachelbel's Canon," recalls a former employe of a local radio station. "That meant I would get 20 calls in the next two minutes from people who wanted to know what it was."

That was a few years ago. Today, presumably, everyone knows Pachelbel's Canon in D. It is heard in the sound track of "To Fly" at the National Air and Space Museum and it is becoming a perennial in commercials. Apparently, the Canon is considered persuasive music; it is being used on television currently to persuade Americans to buy home appliances and to avoid alcoholism.

This month, the Canon passes a new landmark; it finishes its fifth year on the Billboard classical LP best-seller list. This is not the pop chart, so it probably means sales in thousands, not millions, but it is a considerable achievement for a piece of music that the public managed to ignore for nearly two centuries.

Pachelbel's Canon (sometimes spelled "Kanon" to emphasize its archaic qualities and Germanic origins) has been admired for years by scholars and connoisseurs for its solid musicianship and compact, elaborate structure. Why it suddenly escalated to stardom is a bit of a mystery. Why it is on the Billboard list in no fewer than five performances, with a dozen more hovering just below the best-seller threshold, is even harder to understand. The recording by the Jean-Franc,ois Paillard Chamber Ensemble was the first to hit the list and is still there; of the four other records, two are labeled with the name of the Canon and the others are called "Pachelbel's Greatest Hit" and "Greatest Hits of 1720."

The Canon is one of the relatively rare cases in which a piece of music has made the list in its own right. Most classics that become best sellers do so primarily through popular enthusiasm for the performer. Van Cliburn's recording of Tchaikovsky's First Piano Concerto is a classic case. Not that the concerto is box-office poison, but the sales were a vote of support for Cliburn. It was a best seller for years after he won the Tchaikovsky Competition in Moscow in 1959 -- primarily because he was an American in an event that signaled a thaw in the Cold War.

Few competitions since have made such a startling impact, but classical records continue to sell largely because of the performer's personality. Cellist Yo Yo Ma and soprano Kiri Te Kanawa, for example, both have four records on the best-seller list. Te Kanawa has outdistanced both Luciano Pavarotti (who has one bestselling record) and Placido Domingo (who has two). Ma is currently outpacing trumpeter Winton Marsalis, a crossover artist who plays jazz as well as classics and currently has two best sellers.

One CBS recording of Haydn concertos features both Marsalis and Ma. It became an instant best seller -- and not because the public is hungry for those concertos; they have been available for decades in fine performances that were largely ignored. Other well-known personalities with only one current best seller apiece include James Galway, Pinchas Zukerman and Jean-Pierre Rampal. Rampal is represented by the current champion for longevity on the list: Claude Bolling's "Suite for Flute and Jazz Piano," which is on the brink of its 10th year as a best seller.

It doesn't depend entirely on the performer, though. Some pieces of music achieve popularity simply by having attention called to them either in a movie sound track or a television production. Compositions that became media celebrities include Ravel's Bolero (the sound track of "10") and Mozart's 21st Piano Concerto ("Elvira Madigan") as well as Mozart's Clarinet Quintet, which achieved notoriety in the final episode of "M*A*S*H." None of these pieces was exactly unknown before reaching stardom, but they managed to touch an audience enormously larger than the normal clientele for classical music. It is still too early to say whether Mozart (or Salieri) will become a best seller because of the "Amadeus" sound track, but the odds are against it. "Amadeus" is not a mass-market movie.

The Canon in D was featured in the sound track of "Ordinary People," but that was not the beginning of the music's mass popularity. "Ordinary People" dates from 1980 and Pachelbel's Canon made the Billboard list a year earlier. What the movie probably did was solidify and spread the music's already established popularity. In the movie, snippets of the Canon are brought out and subtly altered to fit the mood of the moment. Evidently, that was enough for the Canon to fix itself firmly in the mass subconscious.

Actually, the Canon is only half of Pachelbel's greatest hit as the composer originally imagined it. The music was composed as a Canon and Gigue in D -- a slow movement followed by a fast movement in a form that recalls the pavane and galliard combination of Elizabethan times and foreshadows the Hungarian Rhapsodies of Liszt. Omitting the Gigue undermines the original concept -- gravity and solemnity giving way to lightness and joy -- but the public taste has decided that it wants the Canon without the Gigue, and the public taste will not be denied. It is not impossible to find a record that offers them both together, but you have to hunt for it.

The Canon can be heard in arrangements for nearly every imaginable combination of instruments, and many are featured on the "Pachelbel's Greatest Hit" recording, which is devoted entirely to various versions of the Canon. On other LPs, the Canon (which only lasts about four minutes -- six with the Gigue) is paired with music by composers who range from Antonio Vivaldi to Samuel Barber.

The music was originally composed for three violins and ground bass (cello and keyboard instrument). Its most notable feature is the bass line, given to the cello, on which 27 variations for the violins are hung like pearls in an elaborate necklace. The bass line itself is anything but elaborate. It consists of only two measures -- eight notes of equal length -- which are repeated 28 times without change. The Canon may intrigue violinists musically, though it offers little technical challenge. But it must be hard for a cellist to stay awake while performing it.

Examining the bass line all by itself might remind you of the music of Philip Glass or Steve Reich -- and perhaps its resemblance to these popular modern composers is a key to the Canon's popularity with modern audiences. Glass spends long stretches of time (it can seem like hours) playing three or four notes over and over, with a hypnotic effect. The notes are usually those of a simple chord -- a triad, stretched out into an arpeggio -- and this is essentially what Pachelbel uses.

What happens in the violin parts, while this bass line chases itself in circles, has no resemblance to Glass. After the first statement of the theme by the cello, the violins begin to play variations on the two-bar melody, beginning with the first violin and followed canonically (i.e., in canon, as in a round) at two-bar intervals by the second and then the third. By the seventh measure, the music reaches its full texture: the third violin is playing exactly what the first violin played in Measure 3, the second violin is playing what the first played in Measure 5 and the first violin is launching into the third of its short variations. The violin music becomes faster and more complicated; the notes are shorter, the rhythms less regular, the intervals wider with occasional octave leaps. In any two-bar segment, one hears the theme, placid and unchanging in the plodding bass line, while three simultaneous variations are being played above it by the violins. Toward the end, the violin parts depart from strict synchronization to lead into a decisive conclusion, but the cello continues steadily: D, A, B, F-sharp, G, D, G, A, until it finally lands on the D with which it began -- this time as the root note of the concluding tonic major chord.

Johann Pachelbel (1653-1706), who composed this interesting little piece of musical clockwork, hardly seems the kind of composer who could engage the interest of the Me Generation. He earned his living as an organist and choir director, married twice (his first wife died of the plague shortly before their second wedding anniversary), and begot seven surviving children. One daughter became a respected painter; four sons became noted musicians -- one, Carl Theodorus (1690-1750), an organist in the American colonies. Pachelbel was a friend of the Bach family, godfather to one of Johann Sebastian's sisters and organ instructor to his elder brother Johann Christoph, from whom Bach learned the instrument.

The Canon is hardly typical of Pachelbel's work. He is remembered primarily as a composer of organ music (mostly rooted in hymn melodies) and religious choral music -- though he composed some nonreligious keyboard and chamber works and a bit of ceremonial vocal music for civic occasions.

What he did in the Canon, to become the dominant name on Billboard's best-seller list, looks like a kind of musical hypnosis. There is not only the repetition of a melodic line, but the establishment of a pace that synchronizes with the beat of a human heart in a state of calm. Editors and arrangers generally gravitate to the neighborhood of 60 quarter notes per minute -- which is, by the way, half the speed of the Me Generation's other basic pace, the disco beat. Even with all the elaborate lacework that is spun out by the violins in the upper parts, the basic impact of the music is one of sweet simplicity, calm and relaxation.

It is an effect similar to that of other classical pieces that are perenially popular, if not quite the blockbusters that the Canon has been for five years: Barber's "Adagio for Strings," Bach's Air from the Third Suite for Orchestra (popularly known as the "Air on the G String"); Handel's Largo from "Xerxes" and Albinoni's Adagio, to name a few. Listeners looking for more of what they find in the Canon might sample these or any number of baroque pavanes, sarabandes and passacaglias, the slow movements of Mozart's late piano concertos or Beethoven's Fourth, Seventh and Ninth symphonies, the chorale in Wagner's "Tannha user" Overture or random movements marked "Largo," "Adagio" or "Maestoso." Any one of these might generate the same soothing but essentially irrational chemical reaction and some are considerably better music.

But it is doubtful that any other composer has worked out the recipe quite as precisely as Pachelbel did in his Canon.