WHAT WAS THE secret of Leopold Stokowski's appeal as a musician? There is no mystery about his glamor, the striking appearance, the strength of the man's personality and his attractiveness to capacity audiences. In a day when conductors in this country had not yet become matinee idols, before radio, television, the movies and the instant stardom that today's brand of press publicity can confer, Stokowski was a symbol of arresting elegance.

He was 6 feet tall, his blue eyes were said to pierce, and his head was surrounded with a halo of blond hair. (There was a dramatic parallel between Stokowski's hair and the red-gold aureole that framed the head of Ignace Jan Paderewski, whose fans swooned when their idol hove into sight just as Stokowski's were soon to do.)

There were also the famous hands, of a particular whiteness, which, whether or not they held a baton, were always arresting in the graceful motion with which they wove their mysterious patterns in the air. There was no question about the ineradicable luster Stokowski carried with him. It was as apparent offstage as on, an indefinable but powerful magnetism that has, in recent years, been correctly identified as "charisma" - a personal magic.

But hair and hands, manner and stance are not enough to propel an orchestral conductor into lasting fame. Others, some of them openly imitating Philadelphia's chief ornament, did what they could with what hair they had, tried various dramatic entrances from the wings and practiced athletic leaps onto the podium. None of them succeeded in making music sound the way Stokowski made it sound with the Philadelphia Orchestra.

The fact is that, along with the superstar looks, Stokowski possessed superb conducting technique, and a solid musical education including the study of the violin, piano and organ. His brilliance as an organist carried him to the top level in England, that of Fellow of the Royal College of Organists. In addition to his formal training, however, Stokowski had a marked flair for persuading excellent musicians to play at their best level all of the time, to be glorious soloists or flawless members of an ensemble, and to do it all his way.

Add to this his unquenchable determination to play the exciting new music that was being written in the early decades of this century and to convince his listeners of its beauty and you have a small part of the musician. Flamboyant? Of course he was. He was literally aflame for music.

In his conducting he sought always to give life to the lifeless notes he saw on the scores in front of him. To him the great challenge was to see what he could do with what the composer had set down. This led him to performances of a supreme kind of magnificence in which it seemed as if every nuance of the composer's intention had been found and was being disclosed to the awestruck audience. It also led to to performances in which it seemed clear that the composer's ideas were being inflated, reshaped or misshaped to a point of unrecognizable bloat.

From the evidence available in many hundreds of recordings made under the Stokowski baton throughout almost 60 years, as well as from concerts that remain enshrined in the memories of those who heard them, he was triumphantly right far more often than he was wrong.

Fortunately there is concrete documentary evidence to show us clearly some of the greatest of Stokowski and some of the worst. The Stokowski recording I prize most above all others is RCA Victor's (AVM2-2017) of Schoenberg's "Gurre Lieder," made live at the time Stokowski gave the U.S. premiere of this giant score in 1932.

Listen to this post-Wagnerian masterpiece with score in hand and compare Stokowski's incandescent reading of every measure with more recent recordings by Leibowitz, Frescik, Kubelik and Boulez. These others come out variously antiseptic, pallid or disjointed.

Why the difference? First of all because there is simply no comparison between the Philadelphia Orchestra that Stokowski had built up by 1932 and the ensembles under the other conductors. Far more important, however, is the vibrant plasticity with which Stokowski shapes each page, never letting the music become either routinely settled or nervously unsettled.

The ultimate tribute to his conducting of this extended work is the total rapport between Stokowski and his players and the obvious degree to which the conductor had worked with each of his soloists, down to the final syllable, drawing from them precisely the manner and phrasing that he read into the entire work. Never mind the aged sound, this is a recording for posterity.

In its passion, Stokowski's "Gurre Lieder" is very like a later recording he made of the Love Music from Wagner's "Tristan und Isolde." Here, too, is a kind of glow no other conductor has quite matched, at least on records. It is still available on Odyssey Y-32368.

There are many other recorded performances as persuasive and, in their ways, indictative of the incantational power Stokowski exercised over musicians and audiences alike. For a startling indication of this power, listen to the less famous Houston Symphony under Stokowski's baton on Seraphim 60089 in the symphony, "Ilya Mourometz," by Gliere. Here, deep in Texas, suddenly you can hear the same unmistakable sweep of strings and balance in ensemble so much associated with the Philadelphians.

These sounds are due partly to the conductor's exquisitely acute ear, partly to the freedom he customarily gave to string players to bow "at will" rather than in unison. But if you listen carefully to his recording of "The Planets" by Gustav Holst, made with the Los Angeles Philharmonic, you will hear one of the finest of all accounts of this music, thanks to the fact that Stokowski pays strict attention to dynamic markings that other conductors often ignore.

When it comes to the tougher areas of style, there are no shortages of Stokowski playing standard symphonies in superb manner: His fairly recent Brahms First Symphony with the London Symphony is a reminder of the many years when his first recording of that music stood as a model. His Tchaikovsky Fifth Symphony, played by the New Philharmonia of London, is hard to resist.

Those who have collections of older recordings can easily show you, in the Rachmaninov Second Piano Concerto and the same composer's Paganini Rhapsody, that excellence in partnership - with the composer - as well as in execution, that prompted Rachmaninov to call the Philadelphia the world's greatest orchestra, the only one with which he ever made records.

It is probably fortunate, too, that there are recordings of the very worst excesses of which Stokowski was capable, excesses in both style and performance.The arrogance of the man who did not hesitate to rewrite the chorus parts in the last measures of the Hallelujah Chorus from Handel's "Messiah" gave him special delight in using the full resources of the modern symphony orchestra, percussion included, in mockeries of Bach's Toccata and Fugue in D Minor, and the Passacaglia and Fugue. These are bloated beyond belief, and their arranger gloried in them.

But would yuo believe that another Stokowski recording I would not be without is also a Bach transcription? It is a gem, profoundly moving, an eloquent performances of a chorale prelude. Called "Jesu, was fur mein Seelenweh befallt dich in Gethsemane," it is played by Stokowski and the Czech Philharmonic with "overwhelming beauty, on London 21130.

Similarly, Stokowski "and his string orchestra," on Seraphim 60278, has some of the most beautiful conducting and playing you can hear anywhere. No one else has found, at least on records, the key to the Rachmaninov Vocalise as Stokowski does it here. He also does it superbly when he accompanies Anna Moffo in it and in songs from the Auvergne by Canteloube on Victor 2795.

Stokowski's greatness was firmly grounded on a technique that enabled him to convey to any orchestra "his" way of playing. He was as capable of expertly disciplined performances of Beethoven as he was of the wildest distortion of Debussy. He created a new ideal of orchestral playing and sound. His approach was personal, but so is that of every great interpreter. He was mesmerizing, bewitching, thrilling. As far as I know, it was never said that he was dull.