GREAT WRITERS on music almost invariably reach beyond the special confines of the music world to make vital connections with the other arts. Claude Debussy, to cite a striking example, often sprinkled his letters and essays on music with lively appreciations of Conrad, Chesterton, Mallarme' and other writers who inspired him. Indeed, in his private life, Debussy often shunned the company of musicians, whom he considered narrow and parochial, and befriended novelists, poets and painters. Describing a "magnificent" Palestrina evening in a letter to writer Andre' Poniatowski, he wrote: "Needless to say, there were very few musicians there. Perhaps they had the good sense to know they'd be out of place."

These lines typify the rambunctious drollery of Debussy's letters, which English readers can now enjoy for the first time. In Debussy on Music, Franc ois Lesure and Richard Langham Smith brought out an English edition of Debussy's essays and reviews; now, a decade later, Lesure has collaborated with translator Roger Nichols in an equally valuable and delightful edition called Debussy Letters. Written to friends (especially Robert Godet and Jacques Durand), lovers (Lilly Texier, Emma Bardac), and luminaries from the Paris "Banquet Years" (Gide, Mallarme', Falla, Vare`se and numerous others), these letters cover subjects ranging from the sublime terrors of conducting La Mer and working with the "perverse genius" Nijinsky to the grubby realities of divorce, illness and never-ending anxieties about money.

The stylistic gap between Debussy's letters and reviews is rather slight, for everything Debussy wrote had a vivid, epistolatory informality. Recurring themes are also similar, although they come out in the letters with greater bluntness. Always the revolutionary, Debussy calls in the letters for a total liberation from the old formulas and "false profundity" of the Germans -- including Wagner, whom he saw as a "beautiful sunset who has been mistaken for a sunrise" -- as well as the "hysterical mysticism" of "Gounod & Co." Advocating musical freedom and "beauty of sound" as the only absolutes, he champions very old and recent music -- the "lifegiving delicacy" of Rameau, the "feeling of the infinite" in East European folk music, "the instinctive genius for color and rhythm" in the young Stravinsky.

In an unforgettable letter to Stravinsky in 1912, he recounts how the recent experience of having played the brand new Le Sacre du Printemps with Stravinsky on the piano "haunts me like a beautiful nightmare." Typical of the superb editing in this volume is a dramatic footnote that quotes Louis Laloy, at whose country house Debussy and Stravinsky performed Le Sacre: "We were dumbfounded, flattered as though by a hurricane from the roots of time."

Debussy's most obsessive enthusiasm however, was not for Stravinsky or any other composer but for Poe, with whom he felt a profound, sometimes terrible empathy. In his often spectacular loneliness (Pierre Boulez called him "one of the most isolated composers of all time"), Debussy compared his house with Poe's House of Usher and himself with Poe's disturbed hero. The letters are full of references to operas-in-progress based on "The Fall of the House of Usher" and "The Devil in the Belfry," projects he (unfortunately!) never completed. He described himself in Poe-like terms, as a man "out of the world," "living among apparitions," never able to connect with "real things and real people" -- all qualities that find unmistakable voice in the spectral, otherworldly atmosphere of his music.

In these delectable letters, Debussy engages the real world, his arch-enemy, the only way he knew how: with wit, style and a fixation on strange and rarified beauty.

ANDREW PORTER, music critic for The New Yorker, has just published Musical Events: A Chronicle, 1980-1983, his fourth collection of New Yorker columns. Like the previous compendia, Musical Events collects pieces that begin as reviews but often blossom into expansive essays, not only on the performers (Beverly Sills and Alfred Brendel, for example, in this book), but on the works themselves -- their histories, performance traditions and acoustical peculiarities. A man of broad tastes, Porter makes illuminating connections with language and literature; he tells us how Mozart, in Cosi fan tutte, "proclaims sentiments that Jane Austen and George Eliot would recognize" and how Herman Melville's "networks of motif, allusion, delayed development, and varied restatement soon fascinate anyone accustomed to tracing such things in Wagner or Berg." Complaining about Carlo Maria Giulini's performance of the Beethoven Fifth, Porter demonstrates, in a splendidly lucid analysis of E.T.A. Hoffmann on Beethoven, how the performance was insufficiently "Hoffmannesque." Here, for once, is a critic from whom we can genuinely learn rather than to whom we simply react.

Porter's keenest enthusiasms remain musical theater, pre-19th-century opera and choral music and contemporary music. About the latter he has been reproached, he tells us in his introduction, for being "promiscuously adulatory."

Nevertheless, his championing of Elliott Carter, Pierre Boulez, Roger Sessions and others is a refreshing antidote to what he calls the "New Right" musical culture of the '80s, where the "reactionary" music of George Rochberg and others appeals to "closed, unadventurous minds."

Adventure, along with joy and rapture, is Porter's main esthetic yardstick in judging both music and performance. He admires Boulez's music for its sense of "exhilarating aural adventure"; he praises Karajan's performance of Strauss' normally problematic Alpine Symphony for making it "a vast and elevating adventure -- a Mahlerian excursion into a world of grandeur and picturesque beauty which one could enjoy and marvel at untroubled by any of the reflections that struck Shelley or Mahler when they trod similar lofty paths." But he complains about the New York Philharmonic premiere of Steve Reich's Telhillim because "Mr. Mehta and his players seemed to approach the piece as if its performance were a duty rather than a joyful celebration."

Musical Events, like its predecessors, is itself a cause for celebration. Porter's prose style -- the suppleness with which he moves from the analytical to the personal, from a detailed analysis, for example, of Beethoven piano tradition to a rapturous replay of personal "memory tapes" -- recalls Berlioz, Debussy, Shaw, Thomson and other critics who possessed a real freedom of language and largeness of sensibility. It is a style depressingly rare in contemporary music criticism.

TO THE EXTENT that it has a coherent thread, Philip Glass' new memoirs focus on how his estrangement from the established music community has led him into "innovating" alliances with artists from theater and film. For Glass, the "establishment" was represented by nontonal music of the 1960s -- "music of the past passing itself off as music of the present," in his estimation -- and the alliances he forged with the Mabou Mines, Robert Wilson, Laurie Anderson, and others shaped both the form and content of collaborative works such as Einstein on the Beach and Koyaanisqatsi.

As far as Glass is concerned, the "real events" of the 1960s during his formative Paris years studying with Nadia Boulanger "were happening not in music, but in theater and film. The only musician, besides Boulanger, he seems deeply influenced by was Ravi Shankar, whose unceasing stream of rhythmic pulses inspired the "cyclic structure," "additive process," and other elements in Glass' now-famous minimalist style.

Glass is surely the most commercially successful "serious" composer of our time. (Whether he is the "world's most important active composer," as the jacket claims, is another matter.) As such, his account of how he came to compose Einstein, Satyagraha, and Akhnaten (the libretti of which are reprinted in the book) have a certain automatic importance for the musical record. In addition, Music By Philip Glass gives accounts of Glass' smaller works, as well as brief takes on such subjects as new recording techniques, film composing (Koyaanisquatisi, Mishima), and the evolution of Glass' increasingly pop-oriented vocal writing for singers like Linda Ronstadt.

Unfortunately, none of these topics is developed with much substance or insight. "It was a very conceptual concert," is how Glass describes a performance of his Music in the Form of a Square. "A very neat concert. And it was both visual and musical." Glass' prose style is, well, minimal, little more than an extended resume', a repetitive ticking off of names, places and commonplace observations.

The book also has a subtle self-congratulatory tone rather at odds with the "laid-back," "Eastern" attitude proclaimed in the introduction by Robert T. Jones. "I was part of the new American avant-garde known in Paris, and no doubt I had a following of my own," Glass tells us, recounting his collaboratinon with Robert Wilson on Einstein. "In fact, I had appeared with my Ensemble at Michel Guy's Autumn Festival in Paris, some years before. But Bob was a true enfant terrible of the theater, and in Paris that meant a great deal." Look how avant-garde we are, this books seems to say, even as it chastises other composers for being insufficeintly commercial.

The book does offer some delightful and revealing anecdotes about Glass' odd jobs as a cabbie and plumber, even after huge successes like the sell-out performance at the Met of Einstein. In one instance, a well-dressed lady sees Glass' name on his cab and exclaims, "Young man, do you realize you have the same name as a very famous composer?" Such accounts speak volumes about the real story in this book: the bizarre gap in America between fame and economic reality for serious artists, even spectacularly successful ones.

THE VOLUMINOUS correspondence between Arnold Schoenberg and Alban Berg, two of the most important composers of the 20th century, has been edited and translated with scrupulous care by Juliane Brand, Christopher Hailey and Donald Harris. Written between 1911 and 1936, these 338 complete and 39 abbreviated letters capture the evolution of numerous atonal and 12-tone masterworks, along with the personalities of their creators and the traumatic backdrop of Vienna and Berlin through the duration of one world war and the beginnings of another.

The early letters reveal Berg to be (very much like Webern, Schoenberg's other eminent student) in total thrall to his mentor, whom he believed to be the messiah of 20th-century music. Beginning with the sensational premiere of Wozzeck in 1925, however, which catapulted Berg to a level of fame never attained by his teacher, the relationship changed, with the two men addressing each other in the letters as equals. The final exchange, pathetic and moving, is between Schoenberg and Helene Berg following her husband's sudden tragic death from blood poisoning.

Now that the recent re-embrace of tonality has made Schoenberg-bashing -- or more broadly, serialism-bashing -- fashionable once again, this book takes on special relevance. Several myths about the New Viennese School are undermined here, most notably the cliche' that these composers were always unpopular and "never had an audience." As the letters document, the works of Schoenberg and Berg were always controversial, occasioning more than one "Skandalkonzert," but both composers had passionate advocates and enjoyed major successes. Berg scored a huge hit with Wozzeck and lived to see the beginings of the sensation later to be caused by Lulu; Schoenberg, while quipping that followers were merely "future defectors," enjoyed more modest successes in Berlin, London and Amsterdam with works such as the Chamber Symphony and the Orchestral Pieces Op. 16. Given the challenge posed by nontonal music to a centuries-old harmonic system, the proportion of hostility to advocacy seems relatively mild.

The letters also bring into question the notion that these composers were willfully inaccessible and contemptuous of audiences. Both men write passionately and repeatedly of their determination (often frustrated) to secure "beautiful" and "clear" performances capable of reaching and moving audiences. Ironically, Schoenberg himself complains about how "the modern minded cling to the abstruse and only enjoy it if it remains unclear to them." It is also helpful to see reiterated for the historical record that Schoenberg was by no means implacably hostile to tonality. In a 1934 letter to Berg regarding his Suite in the Old Style, he writes that the fight against "infamous conservatism" must begin by demonstrating "the advances that are possible within tonality if one is a real musician and knows one's craft."

Berg, as his admirers are fond of saying, may well have been "Schoenberg's greatest work," but Schoenberg was clearly the more engaging writer. This is unfortunate, for the great preponderance of these letters were written by Berg, who was always the initiator in the friendship. Even so, The Berg-Schoenberg Correspondence is a fascinating cultural and human document. As composer Donald Harris -- who spent some 20 years on this project -- points out in his introduction, now that "letter writing has almost become a thing of the past, this may well be one of the last times in which so much of history will have been recorded by the protagonists themselves." THE IMPORTANCE of composers' letters is a recurring theme in Music Talks, Helen Epstein's collection of interviews and musical profiles. Horowitz, for example, always reads the letters of composers he performs for a direct insight into their "character" and "taste"; "I don't read books about the composer. I always believe the composer himself and not what others write about him."

Epstein, author of Children of the Holocaust, has a similar attitude toward the performers, teachers, composers, and audio engineers she writes about. After setting the scene with deft, colorful sketches, she steps back and lets her subjects talk directly, often at length. When the subject is shallow and uninteresting (James Galway, for example, explaining how "Sagittareans are born naturally religious"), the results are disappointing. In the case of several performers, however, the talk is not only fascinating but the verbal equivalent of how they play -- Nadja Sallerno-Sonnenberg with slangy abandon and sizzling tension, Leonard Bernstein with eccentric but spellbinding self-absorbtion, Horowitz with an old-world combination of showman's calculation and out-of-nowhere spontaneity.

Music Talks covers a wide range of subjects, including the ethics of record splicing, the perils of music competitions, the "invisible" art of conducting and the addictive joys of teaching. Despite detailed, somewhat grim accounts of musical politics and competitions, Epstein orchestrates her interviews in such a way as to emphasize the mysterious ecstasy of music, what Bernstein dedescribes as the "complete loss of ego" as the performer "becomes" the composer, or what Epstein herself calls the childlike feeling during a great concert that the performers "are somehow immune to things that impede the rest of us," that they are "closer than the rest of us to immortality."

Music Talks is full of light, ironic moments, too, which can be equally revealing and memorable. Here is Seiji Ozawa telling his stiffer conducting students, "Don't be so Oriental." Here is Nadja Sallerno-Sonnenberg explaining how to resist the advances of a lecherous conductor (grab a flight at intermission and be "out of there" before the second half is over). And here is Horowitz describing why he won't play (among many other places) in Japan: " 'You fly Saturday and arrive on Friday,' he says, as if announcing a funeral. 'You have to stay ten days to be right again and that scares me.' "

Whether the talk is whimsical or serious, Epstein captures the meaning and music behind the words, much as a performer reveals the meaning behind the notes.

Jack Sullivan, who writes frequently on musical subjects, is at work on an anthology called "Words on Music."