Three years ago I saw a work by the late Swiss-German artist Dieter Roth that so captivated me that I am determined to write a book just to be able to reproduce it on the jacket. It consists of twenty sausages in assorted sizes, hanging, as in a German butcher shop, in two rows, and is titled Georg Wilhelm Friedrich Hegel: Works in Twenty Volumes. Roth had removed the labels from the individual volumes in a matched set of Hegel’s Werke, and pasted them onto corresponding Würste. Much as I admire Hegel’s Lectures on Aesthetics, it was delicious to see its two volumes chopped into bits, stuffed into casings and displayed as what Roth called “literature wurst.” It was a witty critique of metaphysics that might have caused even those of my professors who were logical positivists to break into thin, sarcastic smiles.

The only piece by Roth I recall having previously encountered was a cheese book–part of a Fluxus collection that had been acquired by the Getty Foundation from the estate of Jean Brown, an avid enthusiast. A Getty official ushered me into a roomful of largely unclassifiable objects, randomly placed on steel shelving. It is a tribute to Roth that his is the only piece I remember. He had flattened a lump of blue cheese in a plastic folder, clasped in a simple cheap binder. I regret never having seen Roth’s legendary 1970 exhibition at the Eugenia Butler Gallery in Los Angeles, which consisted of thirty-seven suitcases in assorted shapes, stuffed with various cheeses, and called Staple Cheese–a play on “steeple chase” to which Roth added “(A Race)” in case someone missed the point. In the nature of things, the art was attacked by flies and maggots, and the stench is reported to have been unendurable. I only read about it in Artforum, after Roth’s death in 1998.

None of these avant-garde creations prepared me for the impressiveness of Roth’s oeuvre as a whole, on view at MoMA-Queens and PS 1 through June 7. If I’d been asked to imagine what an exhibition of Roth’s work would look like, I would have supposed something like that room at the Getty–a jumble of eccentric odds and ends, very few of which would have been seen as works of art before 1960. To my surprise and delight, the author of the cheese book turns out to have been one of the masters of twentieth-century art.

Specialists have employed a German term–entgrenzen–to describe Roth’s procedure as an artist. It means, roughly, to overcome boundaries. Roth’s personality was such that if he encountered a boundary, he would find ways of eliminating it. Fortunately, he came of age in the 1960s, when the spirit of Entgrenzung flourished as never before. Later in the decade Entgrenzung would spread from art to politics, with the rise of movements challenging boundaries of race, gender and sexuality. But its initial impulses were artistic, and can be traced to Marcel Duchamp, whose “ready-mades” blurred the boundary between works of art and commonplace objects like snow shovels, bottle racks, metal grooming combs and urinals. The next important figure in the history of Entgrenzung was John Cage, whose project was erasing the boundary between music, as traditionally defined, and the racket of ordinary life: sirens, coughs, static, whispers, farts. Cage’s composition students at the New School–the cadre of the Fluxus movement, led by Cage’s visionary protégé George Maciunas–went a step further, seeking to erase the boundary between life and art. By the end of that revolutionary decade, there were few if any boundaries left to overcome in art, or for that matter in life.

I have tended to regard boundary erasure in art as largely a Manhattan contribution–downtown through Cage and uptown through Dr. Suzuki’s seminar in Zen at Columbia–but I now see that it was part of the spirit of the times. Roth was a gifted designer with advanced tastes, dedicated at first to Constructivist graphics and concrete poetry, but he had a need for something even more radical, which he found in the work of Jean Tinguely, a fellow Swiss. It has been said that the decade was dramatically inaugurated when, at the opening of Tinguely’s exhibition at MoMA in 1960, his construction, Hommage à New York, self-destructed in the museum’s garden with a lot of smoke and clatter. Roth met Tinguely later that year in Basel. “Everything was so rusty and broken and made so much noise,” he said of Tinguely’s work, likening it to “a paradise that I’d lost.”

It’s tempting to see Roth’s mature work as an effort to re-create that lost infantile paradise by way of detritus, noises and noxious smells. “Paradise Regained” would have been a fitting title for the Roth retrospective in Queens. What one feels is that he turned his entire life into art and created, through his unmatched ludic power, a world of amazing compilations that, like a natural wonder, takes one’s breath away.

Like his peers in Fluxus (a term coined by Maciunas), Roth was reacting against the repressive aesthetics of Modernism, a project that received its clearest formulation in Clement Greenberg’s 1960 essay “Modernist Painting.” Greenberg’s view was that each art is defined through the medium specific to its practices, and that under Modernism each art is obliged to purge itself of everything alien to its essence. In painting, this meant the elimination of illusion, since the painted surface is essentially flat. The ultimate aim was to achieve purity. In a sense, Roth’s Constructivist works were thoroughly Modernist in impulse, exhibiting the clarity of pure design. What Tinguely opened for him was a paradise of impurity, a world of infinite mess–just what he needed to break out of the ascetic order of Modernism.

In 1967 Roth began to craft what he called “Islands,” made out of kitchen scraps, which he nailed to panels painted blue. He was living in Reykjavík at the time, and his inspiration was evidently the Westman Islands–a group of islands off the southern coast of Iceland. Just a few years earlier, the world’s newest island, Surtsey, had emerged abruptly in the Westman configuration and become a kind of natural laboratory, in which the coming of life could be observed taking place. Roth doused the food scraps with sour milk or yogurt and poured plaster over the whole. In no time at all, mold formed, decay set in, and the insects that Roth called his “collaborators” arrived. One might say that “Islands” embodied the spirit of Fluxus in visibly decaying into pools and puddles of slime. And for some years thereafter, Roth experimented with use of food as his medium, making prints out of squashed bananas and exploiting milk, sausage, cheese, of course, and above all chocolate, counting in each case on the processes of rot and decay to help life turn into art–and vice versa.

With his renunciation of beauty as an aesthetic goal, Roth exemplifies what I call the Intractable Avant-Garde. It was one of the marks of Modernist aesthetics to believe that however difficult, however ugly, a work of art will in the end come to be seen as beautiful. The Intractable Avant-Garde rejects this consoling wisdom. Roth once said that the moment something threatens to become beautiful, he stops. He was after a different aesthetic altogether, in Staple Cheese (A Race). Or take his Tibidabo–24 Hours of Dog Barking, a recording of a dog pound on Monte Tibidabo in Barcelona. It’s hard to imagine anything more obnoxious than the uninterrupted barking of dogs, and sustained exposure does not make it more beautiful. What, then, is the work about? In my view it is about freedom, and the cruelty of keeping dogs penned up.

Decay appears to be a major theme in Roth’s work, but he professed to have little interest in it, except insofar as it enabled him to render “the processes of change visible.” Consider, for instance, his innovative use of chocolate. Other artists have been interested in chocolate as a subject. Joseph Beuys’s first multiple was a block of chocolate evoking the privations of World War II, when chocolate carried the meaning of warmth and subsistence: The US Army D ration was a block of chocolate much like his. In her 1992 work Gnaw Janine Antoni used chocolate as a visual metaphor for love. For Roth, by contrast, chocolate was both a subject and a medium in its own right. It connoted mess, and he was not indifferent to its resemblance to excrement (another of his materials), much in the way that Karen Finley smeared herself with chocolate as an emblem of female degradation. His signature work is a bust of himself cast in chocolate. Sometimes he mixed the chocolate with birdseed, so that it might enter the food chain when pecked to nothingness. More spectacularly, he built towers of these chocolate busts, placing five of them at the corners and center of a pane of glass, laying another pane on top of these, placing five more busts on this, until a tower of chocolate heads would reach a certain height. The work is titled Self Tower (Selbstturm). In one of the inner galleries of the MoMA show, the sweet smell of chocolate forms an olfactory aura around a Self Tower built for the occasion. (There is also a tower of self-portraits as lions, also in chocolate.) Inevitably, the weight of the upper shelves pressing down would crush the heads on lower shelves. The glass itself might shatter. “Fluctuations in room temperature, insect activity, and changes in humidity expose the sculptures to a steady process of decay,” the catalogue states. “The ravages of time should not be arrested. The towers are left to deteriorate at the artist’s own wish.”

Readers might jump to the conclusion that the exhibit at MoMA and PS 1 is a depressing affair, a riot of disgusting sensations, not for the faint of heart. In fact, the show is absolutely exhilarating, so full of exuberance, antic invention and the joy of unhampered creativity that it lifts the spirit like little else in recent memory. The first work one encounters at MoMA is a late tapestry portrait of Roth, seated in his studio. He’s wearing a cloth cap and jacket and what looks like a neckpiece in the form of a lobster, and seems engaged in a piece of embroidery himself, spread across his knees. He’s surrounded by the jumble of his studio, which increasingly became the motif of his art. The critic Alfred MacAdam said that Roth’s work reminded him of Courbet’s masterpiece, The Artist’s Studio, in which the artist portrays himself, seated at the easel, while a model looks over his shoulders and all his subjects surround him.

A collaboration between Roth and the weaver Ingrid Wiener, Large Tapestry is a brilliant example of the principle of overcoming the gap between life and art. Tapestry is inherently a collaborative enterprise. As a general rule, the weaver is seated before an upright frame, strung with the vertical warp threads. The artist first prepares a so-called cartoon–a drawing the size of the intended work. This is placed behind the warp, and the artisan, who sees through the warp threads, reproduces the cartoon by means of the colored woof-threads. Instead of drawing a cartoon for Large Tapestry, Roth sat behind the threads, in effect turning himself into the cartoon.

Wiener worked on Large Tapestry from 1984 to 1986. Needless to say, Roth could not have sat still for two years. This left a great deal up to Wiener, who had to keep changing the tapestry to reflect the changes in her subject. Roth compared her work to that of Homer’s Penelope, who unwove the day’s work every night. Roth and Wiener did not so much unweave the tapestry as unweave and reweave life, accommodating the changes in the work.

As Roth’s life and art became increasingly intertwined, the studio became medium and subject. Behind the Large Tapestry, one sees some of his late work, which, whether standing on the floor as sculpture or hanging on the wall as painting, are composites of paint boxes, brushes, cans, bottles, pictures, scraps of writing, drawings, crayons, pencils, frames, a toy ukulele, drafting tools, rulers, smears and slathers of pigment. They are made of what they are about, with little reference to the world outside the studio. It is difficult to think of another oeuvre centered quite so solipsistically on the materials and processes of its own production. Cellar Duet, for example, is an assemblage of tapes, with music by Roth and his son Björn, together with keyboards, players, recorders, amplifiers, toys, wires, again painted into a messy unity with artists’ materials and whatever odds and ends lay ready to hand. In their clotted heterogeneity, these resemble Robert Rauschenberg’s work of the 1950s, but obviously the impulses differ.

At PS 1 there is an even more startling example of Roth’s transformation of life into art. His studio floor, one of the five large sculptures on display, has been turned on edge and placed against the wall. It becomes, in effect, an immense mural, self-mapping Roth’s working space, the varying density of the drips and splatters documenting where the activity of painting was at its most and least intense. In Solo Scenes–an installation of 131 stacked video monitors–we see the artist at work, asleep, on the john–a fly’s-eye view of Roth padding back and forth, drawing, shaping, going about his life over a period of six months. Another work consists of eight projectors continuously showing slides of houses in Reykjavík, 30,000 in all, each with a different building. Image rapidly succeeds image, the carousels clacking away; and though one could, in a sense, see the whole of Reykjavík if one remained in the room long enough, it would be a curiously empty and even dispiriting experience. The capital is shown without inhabitants, and it is ambiguous as to whether its meaning is that the populace turned its collective back on Roth or Roth simply excluded them from his vision. It is in any case a detached portrait of a city, one building at a time, made by someone who shows no sign of being part of the place–though one of the houses must be where he himself worked and lived, and raised his children with a woman he loved.

PS 1 is also exhibiting what must be Roth’s masterpiece–his Garden Sculpture, on which he worked off and on from 1968 until 1996. It is a kind of folie, which may have begun as a platform, a place to sit outdoors beneath the stars, to which disparate parts were added–ladders, wheels, window panes, lengths of dressed lumber, a whirligig, video monitors, potted plants–in a whole of rickety monumentality. It comes with its own workshop, including power tools and rows of electrical cords, as if Roth had become obsessed by a project whose purpose he had long ago forgotten. It feels like a three-dimensional realization of one of Leonardo’s unfathomable drawings–or an outdoor model cobbled up out of scavenged fragments. Kant speaks of art as implying purposefulness without any specific purpose, and this characterizes Garden Sculpture to perfection. For some reason, Bosch’s title–Garden of Earthly Delights–crossed my mind.