Meredith Monk makes the list for 1977's "Tablet"

Throughout much of the 1980s, I was the host of a radio program on New York's WNYC-FM that played a lot of contemporary music. One afternoon, however, I devoted an entire show to works by the 12th-century composer Perotin -- spare, ethereal yet startlingly intense vocal compositions based on the sound (fairly rare in Western music) of stark harmonic fourths. The phone rang and I was confronted with a furious gentleman who claimed that I'd ruined his drive home (and, one might have surmised, his life as well). He promised he would never again contribute to public radio until we stopped playing what he called "all that damned new music"!

Obviously, 800 years on, Perotin is still not an "easy listen." In fact, almost any musical language with which we are unfamiliar will seem "new" to us at first. But let's face it: For many well-disposed music lovers, this has been an especially tough century. Indeed, as far as the absorption and appreciation of 20th-century opera and concert music go, a lot of people out there pretty much missed it.

Exactly why this happened can and will be debated for many years to come (some possible reasons -- the collapse of music education, the split between the "high arts" and popular culture, the decline of the concert and the increased importance of mass media, and the perceived impenetrability and/or ugliness of much 20th-century creation). In any event, rightly or wrongly, many listeners never came to terms with the main classical music trends of this century.

This will not be one of those "Here are some nice, not-too-frightening recent works to pull you into your own century" articles. I approve of such ventures entirely (my own "getting started" list might include the music of Olivier Messiaen, Henryk Mikolaj Gorecki's Symphony No. 3 and some of the film scores of Philip Glass).

Instead, let's break out the hard stuff. For once, let's give frank radicalism its due -- without apology and without sugarcoating. The following is a list of substantial 20th-century pieces that make no special effort to be liked. Indeed, if I may anthropomorphize for a moment, they really couldn't care less whether you like them. These are works that were bold, original and, in some cases, downright horrifying to their audiences when they were first performed, and even today a first encounter with them will likely inspire anything from intrigue to befuddlement to inchoate fury.

No attempt has been made to be comprehensive, nor have I attempted to present only "the best" 20th-century pieces. (Great works of art are not necessarily radical; for example, Richard Strauss's nostalgic, deeply conservative "Four Last Songs" speak just as profoundly to us as his manic, off-the-wall "Elektra.")

Virgil Thomson, above, and Gertrude Stein composed "Four Saints in Three Acts"

Moreover, the shock has worn off of some once-notorious pieces. In 1927, George Antheil's "Ballet Mecanique" appalled traditionalists with its use of sirens, car horns and multiple pianos; today, in the era of computer sampling, this seems little more than a collection of gimmicks and the work barely holds our interest.

A much greater piece, Stravinsky's "Rite of Spring," was so influential in its time that listeners, hearing it co-opted and recycled again and again by composers of every stripe, have become accustomed to its language. While we admire "Rite" today, it no longer shocks us silly (indeed, Walt Disney incorporated it into "Fantasia" more than 50 years ago -- and how disconcerting can a Disney soundtrack be?). And the once-recalcitrant works of Pierre Boulez -- "Pli Selon Pli," "Le Marteau Sans Maitre" -- now sound almost pretty, and very much in the French tradition of Debussy and Ravel.

Still, here are a few important 20th-century pieces, in chronological order, that have never quite been tamed. Indeed, the subversive in me hopes they will inspire perplexed listeners and angry calls for at least 800 years.

Charles Ives: "The Unanswered Question" (1906). There is still some debate about whether Ives was a genuinely visionary musical thinker or merely a primitive dabbler who occasionally hit on a good idea. In general, I lean toward the dabbler theory; such works as the "Concord" Sonata seem arbitrary and incoherent -- one dissonance as satisfactory as another -- and his endless quotation of hymn tunes and Civil War songs, a sort of stylized, cosmetic Americana, wears thin very quickly. But there are a few Ives pieces that demand our respect and "The Unanswered Question" is one of them.

Scored for orchestra and solo trumpet, it begins with a slow, seraphic, barely audible chorale, played by the strings. A quizzical, angular phrase for trumpet poses the musical "question," which is "answered" by a gaggle of wind instruments. This is repeated, with greater intensity, and the piece eventually devolves into a controlled cacophony, after which it regains its gravity, repeating the question again before dying out into a cosmic stillness.

This is great music in a number of ways. It is both consonant (the soft bedding of the string chorale) and abrasively dissonant (the "questions" and "answers" are naked and awkward). It is a work that creates its own form, perfects it, then breaks the mold: There was nothing like "The Unanswered Question" before it was written, and, by its very nature, it can never have a legitimate sequel. Finally, it conveys, in a manner unlike any other piece I know, the vastness of infinity, at once mystical and humbling, all-inclusive and achingly lonely. (Recommended recording: Leonard Bernstein, New York Philharmonic. Sony Classical. To hear a free Sound Bite from this selection, call Posthaste at 202-334-9000 and press 8174.)

Richard Strauss: "Elektra" (1908). This is an utterly horrible piece; it is also magnificent. Strauss and librettist Hugo von Hofmannsthal took Sophocles' tragedy "Elektra," set it to music that combines graphic violence with convulsive sexual ecstasy, and created the most disturbing opera in the repertory. From the slashing outline of the D minor triad that opens the opera (rather as a punch in the face might be said to open a dialogue) through the triumphant, frazzled, obsessively reiterated C major chord that concludes the slaughter 80 psychotic minutes later, "Elektra" is a study in overkill so bloodthirsty that it is not surprising that Strauss completely changed course once he had this out of his system (his next opera was "Der Rosenkavalier," a Viennese comedy of manners!).

A good "Elektra" should leave an audience speechless. This is the most unhealthy of masterpieces; it incites us, with huge orchestra, chorus and a cast of iron-voiced soloists, to cheer on Elektra's revenge, a brutal matricide, all set to music that is both enormously sophisticated and primal as hell. (Recommended recording: Birgit Nilsson in the title role, with the Vienna Philharmonic under Sir Georg Solti. London Records. Soundbite code: 8175.)

Jean Sibelius: Symphony No. 4 (1911). Another one-of-a-kind. Sibelius had earned a world reputation with the romantic, somewhat Tchaikovskian grandeur of such works as "Finlandia" and the Symphony No. 2. In 1911, this dour, spare, austere and weirdly beautiful score came as a complete surprise to Sibelius's listeners and critics (many of whom were vociferous in their denunciations), and it remains unsettling and enigmatic to this day.

In the 1940s, John Cage put household items in the strings of a piano to make new sounds.

The Fourth Symphony has been likened to a sort of musical cubism, and as such analogies go, this is a fairly good one. The first movement in particular is built block by sonic block, with an absolute minimum of padding; rarely has a composer said so much so tersely. The second movement always seems to be about to break into a waltz, but it never quite gets there and ends abruptly, with dark, disturbing, birdy tritones and a peremptory roll from the timpani. The third movement is another study in delay -- in this case, we wait for a long, sweeping melody that climbs mournfully for 2 1/2 octaves and then dies away. And what can all those bells be about in the finale?

The entire symphony is very strange; "There is nothing, absolutely nothing, of the circus to it," Sibelius once said. To be sure, and it is as mystifying to a general audience today as it was when it was written. (Recommended recording: Herbert von Karajan, Berlin Philharmonic. EMI Classics. Soundbite code: 8176.)

Arnold Schoenberg: "Pierrot Lunaire" (1912). Even Schoenberg's greatest admirers admit that "Pierrot Lunaire" is difficult. The composer Charles Wuorinen once compared the experience of listening to it to that of befriending a porcupine. Another composer, George Perle, acknowledged that "Pierrot Lunaire" is "not a work that one ever gets used to." So why, almost 85 years later, with Schoenbergism largely abandoned as a musical movement, do we still care about "Pierrot Lunaire"?

Because it is there, that's why. This bizarre, arty, expressionist song cycle may not be Schoenberg's most appealing piece but it is undoubtedly his most radical -- indeed, it is the culmination of a certain strain of Viennese decadence. Here, the composer truly breathes the "air of other planets" that he alluded to in his String Quartet No. 2; this is cabaret music for Martians. Schoenberg set 21 poems (by Albert Giraud) in what he called sprechstimme -- a form of speech-song where the vowels in each word momentarily touch on the indicated pitch, then fall away from it for a sort of creepy-crawly, haunted-house effect that works well in the right material. This is the right material. (Recommended recording: Jan DeGaetani, with Arthur Weisberg and the Contemporary Chamber Ensemble. Nonesuch Records. Soundbite code: 8177.)

Virgil Thomson/Gertrude Stein: "Four Saints in Three Acts" (1928-34). To begin with, the opera is in four acts (but only one intermission) and has more than 30 saints in it. Stein's words come across as genial, cracked logorrhea ("To be asked how much of it is finished. To be asked Saint Teresa Saint Teresa to be asked how much of it is finished. To be asked Saint Teresa to be asked Saint Teresa to be asked ask Saint Teresa ask Saint Teresa how much of it is finished"). Thomson's music is straightforward, deceptively uncomplicated, chock-full of C major. The opening night cast was an all-black one (a tradition that has been preserved in later productions), the sets were cellophane, and nothing really "happens" in the sense of a recognizable plot. All the standard rules of musical theater were at least ignored, sometimes deliberately broken.

"Do not try to understand the words of this opera literally nor seek in the music of it undue references to modern Spain," Thomson wrote. "If, through the poet's liberties with logic and the composer's constant use of the plainest musical language, something is evoked of the inner gaiety and the strength of lives consecrated to a non-material end, the authors will consider their labors rewarded." Today, "Four Saints" seems the great-great-grandparent of performance art, maintaining a freshness, clarity and contemporaneity that is absolutely up to the moment. (Recommended recording: Orchestra of Our Time, conducted by Joel Thome. Nonesuch. Soundbite code: 8178.)

Aaron Copland: Piano Variations (1930). Forget such gentle, homespun scores as "Appalachian Spring" and "Quiet City." When Copland was in the mood, he could be as ferocious and uncompromising a modernist as America has produced. The Piano Variations, some 12 minutes of coiled, tactile fury, was once described by Leonard Bernstein as "a synonym for modern music -- so prophetic, harsh and wonderful, and so full of modern feeling and thinking."

Copland starts with a gonging four-note cell that sounds a little like the familiar "Westminster Carillon" turned on its head. On this, he constructs 20 succinct variations that build to a conclusion that is little short of cataclysmic. And yet there is an overriding structural clarity to the music: "As I listen to the Piano Variations," the author (and sometime composer) Paul Bowles once said, "I'm aware of every detail of its construction; its beams and struts are beautifully visible, unmarred by any ornamentation." (Recommended recording: Leo Smit. Sony Classics. Soundbite code: 8179.)

John Cage: Sonatas and Interludes for Prepared Piano (1946-48). It sounds like one of the dada stunts for which (unfortunately) John Cage would later be known: take an ordinary piano, then insert screws, erasers, nuts, bolts and pieces of plastic among the strings, and then sit down and try to play it. In fact, Cage had found a "whole new gamut of sounds, which was just what I needed," he wrote. "The piano had become, in effect, a percussion orchestra under the control of a single player."

Those who dismiss Cage's later work out of hand owe it to themselves to listen to the music he wrote in the '30s, '40s and early '50s, for it is charming, dynamic, attractive and unfailingly original. His longest and most ambitious piece from this era is the set of 16 sonatas and four interludes he created for the "prepared piano" in the years just after World War II. They were written at a time when Cage was just becoming interested in Zen philosophy: "I decided to attempt the expression in music of the permanent emotions of Indian traditions: the heroic, the erotic, the wondrous, the mirthful, sorrow, fear, anger, the odious and their common tendency toward tranquility." Strange and sublime noisemaking, this hour-long exploration can stand as Cage's testament -- "The Well-Prepared Piano." (Recommended recording: Maro Ajemian. Composers Recordings. Soundbite code: 8180)

Karlheinz Stockhausen: "Song of the Youths" (1955-56). On first hearing, it may sound like Munchkin babble -- and it drives unsympathetic listeners absolutely up the wall. Still, upon reflection, this is one of the great masterpieces of electronic music -- somber, specific and, on some curious level, deeply lyrical. Stockhausen took sung sounds and electronically produced noises and built them into a space-age devotional epic based on the Book of Daniel, the "Song of the Men in the Fiery Furnace." ("Whenever speech momentarily emerges from the sound-symbols in the music, it is to praise God," Stockhausen observed.)

A good deal of Stockhausen deserves rediscovery -- his glassy, hyperactive piano pieces; "Stimmung," an amazing proto-minimalist work for unaccompanied voices; "Hymnen," a vast, moody mid-century electronic tour of the world through its national anthems. It is unlikely that he will ever be a popular composer, but he is a significant one. (Recommended recording: composer-supervised on Deutsche Grammophon. Soundbite code: 8181.)

Steve Reich: "Four Organs" (1970). If you respond to musical minimalism, you likely find it both hypnotic and invigorating; if you don't, you probably find it more boring than "Forrest Gump," white guilt and the collected works of Enver Hoxha put together. Either way, you can't get much more "minimalist" than "Four Organs."

Reich once described this work succinctly -- "short chord made long." From a technical standpoint, that pretty much sums it up -- four organs, kept in time by steadily shaken maracas, repeat a single chord again and again, bringing in different voices for different lengths of time until we have examined the structure from what seems every possible vantage point. But this cannot convey the score's pristine formal perfection; the suspense it builds in a susceptive listener; the ecstasy one feels as the organists dive slowly, deeply, inexorably into Reich's wonderful chord and then come up renewed. I'm mad for "Four Organs"; however, it is fair to warn the reader that those who aren't mad for "Four Organs" usually despise it and that performances have provoked near riots. (Recommended recording: Steve Reich and Musicians -- including the young Philip Glass! Mantra. Soundbite code: 8182.)

Meredith Monk: "Tablet" (1977). "Tablet" begins with four women furiously shrieking out a cappella syllables as loudly as possible. The effect is both bracing and riveting (and has scared at least one 5-year-old out of the room and under his covers). Thereafter, however, this is a rich, warm, variegated and startlingly evocative piece and, for me, Monk's most satisfying work. But its strangenesses are genuine and manifold: "Tablet" is scored for soprano recorder, three pianists (who share one piano) and four specially trained voices singing, parrying and babbling made-up words and nonsense syllables.

Monk is a true original. She follows no leaders, leads no followers. In addition to her work as a composer, she is a choreographer, playwright and filmmaker, all of which she pursues with the same single-minded sense of purpose she devotes to her music. You may love her work or you may detest it, but you certainly haven't heard it before. Nor will it soon fade into the background. (Recommended recording: "Songs From the Hill/Tablet." Meredith Monk. Wergo Records. Soundbite code: 8183.)