The music of John Cage is still considered avant-garde by some, even though he passed away 20 years ago. His works continue to stretch most people’s definitions of “real” music. Sunday night’s Orchestra Uncaged at the Sottile Theatre provided firm evidence that more mainstream classical music fans are listening and learning from him these days.

This event also marked the first time in my festival memory that a really big orchestra, nearly the full Spoleto Festival Orchestra, has performed new or even avant-garde music. John Kennedy’s Music in Time series usually happens in a much smaller venue, playing with smaller ensembles to smaller crowds. But with Kennedy’s appointment as Spoleto’s resident conductor, we have reason to hope that more events of this kind will be forthcoming. If the success of this concert is any indication, they definitely will be.

The work from Cage that we heard — Twenty-Six, Twenty-Eight, and Twenty-Nine — requires a little advance skullwork if you want to understand how it functions. The title’s three numbers refer to several things. Each is simultaneously the name of one of the work’s three subordinate orchestras, the number of players in each, and the length of time (in minutes) that it plays. Thus, for example, ensemble Twenty-Nine contains 29 players and performs for exactly 29 minutes. Rather than playing end-to-end here, the orchestras “nest” within each other, shortest to longest, with the longest starting first and the others starting in time to avoid outlasting the longest. Each ensemble has its own specific orchestration: 26 violins in Twenty-Six; 28 wind and brass players in Twenty-Eight; and 24 low strings, two percussion, two timpani and piano in Twenty-Nine. The players have specific, notated “events” to work with: note-sequences (or rhythmic sequences for percussionists), ranging from single notes/beats to extended phrases; there’s no free improvisation. Each player delivers his/her events within flexible time-brackets governed by chronometers or stopwatches and is free to choose the beginnings, ends, and durations of their events within the limits of their specified time-brackets. At any given point in time, many of the musicians are momentarily silent. Thus there is no need for a conductor; indeed, any maestro would be very hard-pressed to keep track of or cue 83 distinct parts in performance. Oh, and all this flexible time-bracket business means that no two performances of the piece will ever sound exactly the same.

Are you thoroughly confused yet? Mind you, the above attempt at an explanation covers only the basics. This work can be performed in several other configurations as well, with an even more bewildering array of mathematical and musical permutations. If you want to explore those, read the more detailed event program notes in your big festival brochure. I’m sticking only to how it was done on Sunday night.

Down to the music itself. Up front, where you would usually find a conductor, there was a console or control panel of some sort, which the audience could see only from the rear. The piece began when a member of ensemble Twenty-Nine came forward to switch on their 29-minute chronometer. Then, in less than a minute, a member of Twenty-Eight did the same, followed by (within three minutes) the designated Twenty-Six person; such timing was necessary in order to “nest” the ensembles successfully. Thus the music slowly unfolded, as more and more musicians “folded” into the overall flow, steadily layering into a constantly shifting, pulsing sonic morass that’s perhaps best described as “harmonic anarchy” (rhythmic anarchy, too). Indeed, there was no discernible melodic or rhythmic structure.

Countless sounds and combinations thereof hit my (at first) bewildered ears. I perceived a sort of foundation that consisted of mostly sustained passages, both droning single notes and multi-note phrases. But it was laced throughout with more intrusive, sonic punctuations that consisted of single instrumental squeaks, bleats and yawps, plus various percussive beats. There were abrupt starts, stops, crescendos, dropoffs, and stray melody-snippets looking for a home. The net result was a constantly shifting, simmering aural tapestry that no ear could effectively keep effective track of. Once I realized that, it hit me that any attempt to actually analyze all this in standard musicological concepts and terms was absolutely futile. And so there was nothing left to do but sit back, close my eyes, and let the entire pot of sonic soup wash over me.

The music conjured up nocturnal scenes complete with buzzing bugs, hazy mountain vistas, stretches of lonely highway, chirpy little birds, high-flying airplanes, stretches of outer-space etc., etc. At times, it seemed that I was drifting through time and space, at one with the cosmos. The overall sense of serene peace (despite occasional jolts) was distinctly spiritual. And then it was over, leaving me feeling cruelly bereft. Where did the time go? It seemed the quickest 29 minutes I ever lived through.

After intermission, it was back for some remarkable music from Jonny Greenwood of Radiohead fame. The large string orchestra was in a more customary configuration with a conductor this time. The first work, 48 Responses to Polymorphia, was a doozy. The number 48 apparently refers to the number of string players employed; there were nine sections or movements to the piece. Several modern composers have experimented with the basic musical concept behind this one, namely beginning with a moment of musical coherence (here, a simple C-major chord or a Bach-like chorale based on it) and distorting it in different ways, transforming it into often chaotic and hard-to-define sonic structures before bringing it back into coherence (or not). His players having been given specific distortion techniques and instrumental effects (like different bowing techniques), Kennedy would sweep his hand broadly, from one side to the other, over the entire orchestra, cuing the players to gradually implement one or more such techniques as his arm swept past them. Some of what we heard had kind of an electronic-sounding edge or buzz to it — yet the players were not amplified or otherwise tampered with electronically or digitally.

Another apparent trick was accomplished with microtones: making a simple note or chord evolve, sliding, into a seemingly shapeless tone-cluster and then bringing it back into coherent diatonic focus. Imagine looking through the viewfinder of a camera or binocular eyepieces while twiddling the focus knob, watching what you’re looking at snap in and out of focus. Translate that visual concept into musical sound, and that’s something like what we heard here. The orchestra’s lush string tones sounded absolutely gorgeous, and there were moments throughout the piece of stunning beauty and impact.

For the final selection, the rest of the orchestra returned to the onstage. Commissioned by the BBC, Greenwood’s Doghouse was also a musical marvel, based on the general impression or feel of lighter music, as if from a radio/TV/theatre orchestra or a typical vintage dance band. But it’s anything but a blatant pastiche of actual music of that type. The composer sought to make original musical suggestions of such material, while imagining the state of the well-worn sheet music for it after decades (or longer) of storage in some dusty old BBC music archive — brittle, tattered, torn, or even missing pages that can’t really be used. From there, Greenwood subjected his ideas to some of the same sorts of distortions heard in the previous piece. Fractured music or not, the orchestra, under Kennedy’s deft conducting, sounded fabulous, and it looked like the players were having a ball with it.

The evening was a distinct triumph, not only for Spoleto, Kennedy, the SFO, and Jonny Greenwood, but for the spirit and memory of John Cage and his art. Few other composers, past or present, have managed to shake up traditional musical concepts and definitions like he did (and is still doing), and force people to expand their musical horizons. Driving home afterwards, I couldn’t help but reflect on the evening’s other triumphant aspects, like the fact that the program not only filled a sizeable theater to near capacity but kept them glued to their seats for the duration and generated much applause throughout, including a noisy, enthusiastic half-standing ovation at the end. I don’t recall seeing anybody walk out. Thanks in large part to Kennedy’s advocacy and superhuman effort, ever more of us are happily clambering aboard the new music bandwagon.