The maturity of the late works of significant artists does not resemble the kind one finds in fruit,” Theodor Adorno once wrote. “They are, for the most part, not round, but furrowed, even ravaged.” The current exhibition at the Tate Modern in London devoted to the unclassifiable American artist Joan Jonas, 81, is an occasion for thinking again about late works—and especially in ways that Adorno could not have done in 1937, when he was writing about Beethoven’s late style.

That’s because Jonas does strange things with time. More than the objects she makes or finds, more than the moving and still images she creates with a camera or by her incessant practice of drawing, more than the bodies (her own or those of others) that appear in live or recorded performances, more than the words and sounds that accompany them, time itself seems to be the main material Jonas works with, manipulating it as a sculptor might mold, tear, and recombine bits of clay. “I deal with space in a very physical and a conscious way,” she says in a conversation reprinted in the exhibition’s catalog. “In video and film and performance, time accompanies that. How long to move from here to there? How long does it last? Give it time. Flash an image—a memory. I work with time, but I don’t plan ahead of time. I juxtapose different times, curious about how they’re going to affect each other.”

When what we experience as the present is always a palimpsest of other times—of recurrent pasts and emergent futures—can time really be the linear sequence we imagine? If linearity is only one aspect of time as we experience it, and time’s simultaneity is just as significant, then we should be wary of parsing an artist’s oeuvre into early and late phases, or at least careful that we’re not looking for earliness and lateness in the wrong places. Memory puts the presentness of the present into question as much as it does the pastness of the past, and so does forgetting. What’s lost when memory is suppressed is the knowledge captured by William Faulkner’s famous observation that “The past is never dead. It’s not even past.” It remains with us, however elusively, like the ghosts that pass through so many of the stories that inspire Jonas.

Perhaps it is the case that Jonas has been making her late work all along, or that the work she was doing in the late 1960s and early to mid-’70s might, according to Adorno’s formulation, be later than her art of more recent decades. Jonas’s chronologically early works are the ones that are expressionless and distant yet somehow ravaged. They are the ones in which the artist’s subjectivity is revealed mainly by what Adorno calls “the irascible gesture with which it takes leave of the works themselves. It breaks their bonds, not in order to express itself, but in order, expressionless, to cast off the appearance of art. Of the works themselves it leaves only fragments behind, and communicates itself, like a cipher, only through the blank spaces from which it has disengaged itself.”

The blank spaces in which we see Jonas’s subjectivity most directly appear in the earliest piece in the Tate exhibition (which was curated by Andrea Lissoni and Julienne Lorz and will be on view through August 5, after which it will travel to the Haus der Kunst, Munich, and the Serralves Museum of Contemporary Art, Porto). Wind (1968) is a silent black-and-white film—displayed here on video—that shows a group of black-caped figures, two of them with mirrors covering their costumes, as they perform (or attempt to perform) a sequence of mysterious, sometimes comical-looking, perhaps ritualistic movements on an empty beach on Long Island’s North Shore. The wind blows so hard against the performers that it sometimes seems to thwart their efforts, yet at other times it appears to be a necessary partner in their strange dance through this inhospitable winter landscape at the water’s edge. Jonas calls it “a comedy of chaos,” but its comedy is austere and rueful.

For Adorno, it is symptomatic of a stereotypical misreading of late works as expressions of untrammeled subjectivity that they are thereby “relegated to the outer reaches of art, in the vicinity of document,” but this seems unavoidable if he is right that they record the process of shedding artistic appearance and leave “only fragments behind.” As is common in exhibitions that include performances and other similarly transient works, a section of documentary photographs of video recordings and descriptions of several of Jonas’s performance pieces from 1968 through 1980 has to communicate the nature of these works by indirection. Those of us who were not there at the time have to try, from what is truly a handful of fragments, to conjure what they might have been, to fill in the blanks. In these images, the mostly urban backdrops are often just as striking as the actions they frame.

For Jonas, now, in retrospect, the blank spaces of the city where most of the pieces were made emerge as active forces in the creation of the works: “some parts of New York looked like ruins,” a wall label quotes her as saying, referring to the city as it was in the 1960s and ’70s. (It is one of the exhibition’s strengths that the labels feature the first-person voice of the artist herself.) “These were places to explore. SoHo was relatively empty, and artists were able to move into old, recently abandoned factory lofts there that had the beauty of another time. It wasn’t expensive to find a place to perform or exhibit one’s work, and you could work on these streets, lots and docks without an official permit. My performance and video reflected that setting. It was an atmosphere grainy and rough.”

“Grainy and rough” is how I would characterize the photographs themselves, as well as the films and videos made in these early years—it’s almost the essence of their style. In a 2003 interview with Hans Ulrich Obrist, reprinted in the Tate exhibition’s catalog (which also reprints an interview that I did with Jonas last year), she recalls how “that grainy quality of early video was so strange, even otherworldly. That was the aesthetic that we all really liked. Filmmakers hated it, of course.”

Jonas’s aesthetic of fragments was a prolongation of modernism, and less in keeping than might at first have been obvious with the burgeoning postmodernism of the time. Her artistic aspirations were very different from those of the various types of blunt-impact minimalism in works by her colleagues in that era—of a sculpture like Richard Serra’s 1968 Prop, a rolled sheet of lead holding another sheet flat against the wall, or a composition like Philip Glass’s Music With Changing Parts (1970), with its intricately patterned rhythmic modules creating unexpected shifts of texture within an unremittingly consistent pulse.

Jonas has repeatedly emphasized the importance of modernist poetry for her developing aesthetic; Yeats, Williams, Pound, and H.D. are the names that crop up again and again in her interviews. That means her sense of “image” has always been as literary as it is visual—what Pound called “an intellectual and emotional complex in an instant of time.” And it means that, like Williams, Pound, and H.D. (whose long 1961 poem Helen in Egypt became the inspiration for Jonas’s 2002 installation and performance Lines in the Sand), Jonas would eventually expand from a poetics of the single, condensed image to one based on a multitude of images in contiguity, implying that each instant of time might in some way be simultaneous with, or in communication with, many others.

Another of Jonas’s acknowledged literary progenitors is Jorge Luis Borges, whose intellectual games with time and space suggest an even more radically nonlinear sense of temporality than that of his American and Irish predecessors. Think of his story “The Aleph,” which presents a point in space where all other points coexist, or of his “The Garden of Forking Paths,” which suggests that time can be conceived as the simultaneity of all possible outcomes of any given action.

The most recent installation in the Tate show, Stream or River, Flight or Pattern (2016–17), which was shown last summer in New York, contains three video projections on freestanding screens that are surrounded by enlarged drawings of birds on wooden boards and paper kites, made in Vietnam, hanging from the ceiling. The imagery in the videos—now crisp and clean enough to satisfy any filmmaker—spans the globe: We see what are essentially portraits of the feathered inhabitants of a bird sanctuary in Singapore, as well as mosaic floors in Venice and the redwoods of California, to name a few. Some of the most striking footage, filmed in a village near Hanoi, shows a ritual in which large, colorful paper models of animals are taken first to an altar, then to a pyre, where they are burned. The strange thing is that this ceremony is carried out in an absolutely unceremonious way, as if the sacrifice of elaborate paper simulacra, made for no other purpose but sacrifice, were of no importance, just a banal necessity like taking out the trash.

These vérité shots from Jonas’s travels are interspersed with others, taken in a studio in New York, in which a couple of children, and the artist herself, perform their own strange, quasi-ritualistic but also gamelike sequences of movements while similar travel footage is projected behind and onto them. The “real” performers become something like ghosts haunting landscapes to which they are foreign and which their gestures can’t affect.

As children, the performers represent the future, but here they seem cut off from the present, as does Jonas, around 80 as she was making this piece. There is a poignant sense that one is always too early or too late to be at home in the now; and, as a viewer wandering through this environment of juxtaposed images, moving and still, one is always at a distance from things—objects that are doubles of other objects and images that layer various traces of various times in a single frame.

In Stream or River, Flight or Pattern, as in other recent works—among them Reanimation, which began as what Jonas calls a “lecture-performance” in 2010 and took its present form as an installation in 2013; or They Come to Us Without a Word, not shown in London, which she made for the US Pavilion at the 2015 Venice Biennale—Jonas manifests, in an oblique way, a preoccupation with our environmental crisis. Not that there’s any preaching about climate change, but the recurrent (I could almost say obsessive) circling back to images of birds, trees, bees, and the land in general takes on an elegiac tone, as if these life forms, which we need much more than they need us, were in the process of taking leave of their connection to the world of humans.

Is all this beauty nearing its end? Jonas’s camera gives things a lingering look, as if in secret hope that a moment of perception could hold for eternity. Stream or River, Flight or Pattern could be a late work, not just in the career of its maker, but in that of the civilization of which it is a product. That’s a kind of late work that Adorno might not have been able to imagine in 1937, even as the disaster of World War II was looming.

With its many elements spread throughout a room, Stream or River, Flight or Pattern offers no perspective from which things resolve into a whole. Each of its videos can command your rapt attention, yet in the back of your mind, and perhaps the corner of your eye, the others solicit equal consideration; concentration and its dispersal are solicited in equal measure. That’s also one of Jonas’s techniques for populating her images with the ghosts of others—the ones that might be reeling off behind you or off to the side. But other works of hers put the viewer in a fixed relation to the image. I’m thinking in particular of a group of pieces called “My New Theater,” which she’s been making occasionally since 1997.

These are long wooden boxes, each of which houses a video screen that’s set at a distance from the opening through which one views it. It’s almost as if the device funnels its imagery directly to the eye, while at the same time maintaining an insuperable distance between them. Set in the space between the screen and the viewer are occasionally various small props and sometimes pictures. Depicted in the videos are mostly a few simple actions, such as tap dancing or drawing, that turn out to be more complex than they might at first seem.

One of the most charming of these pieces is My New Theater VI: Good Night Good Morning ‘06 (2006), a sort of remake of a work from 30 years earlier. In the video, Jonas’s reflection appears in a convex mirror as she bids herself good night, then good morning, night after night and day after day. We see her groggy and rumpled in the morning, drowsy as she’s preparing herself for bed. The artist, genially informal for once, is performing the self she is when she’s not in performance, the self that’s not seen by anyone but her mirror (and her dog). Each day the position of the mirror changes, so we keep seeing the same room from a different angle. It’s like a running joke that’s always told a little differently. But is Jonas talking to herself, to the mirror as a sort of imaginary interlocutor, or to anyone who might happen to see the piece?

Borges was the reason I started using mirrors,” Jonas has said. It’s the most persistently recurring metaphor or device in her art, one she began to use in 1968, often to produce a note of unease. Jonas introduces the mirror to fragment, obscure, or recompose the image; rarely does she use it in the disarming manner of My New Theater VI. Video, too, is one of her mirrors—and, of course, until flat screens became the norm, the surface of a video monitor was typically convex. One of the most striking of Jonas’s early works is titled Glass Puzzle II (actually, it’s dated 1974/2000—that is, as both an early work and a fairly late one, in accord with Jonas’s way of turning time back on itself). The black-and-white video shows the artist carrying out a sequence of movements and actions while another performer, the painter Lois Lane, attempts to “mirror” her gestures. But their actions are both seen, as it were, through a glass darkly—shot off a monitor, which we can tell because of the reflections.

Jonas has spoken of how video can create “an illusion of boxed space,” explaining that “I wanted to alter it; to climb inside, to use the reflective surface, to tape the layers of reflection and interior image fed to the monitor by a second camera.” In the installation that she built around this single-channel video in 2000, she added a small monitor showing color footage of some of the same activity, along with props that seem to have emerged from the grainy footage of decades earlier—yet in this context, the material objects can be seen as mere images of the ones glimpsed in such an intangible way in the video. If the 1974 Jonas wanted to climb inside the illusory box and see what its limits might be, the 2000 Jonas opened that box and spilled out its contents in space—without accepting the notion that space’s three dimensions are any more real than the image’s two. This is one of the underlying stories of the exhibition and of Jonas’s career: how the video art of the 1970s unfolded itself from inside the monitor to occupy the bigger box of the room as what we now call video installations—a genre that Jonas and a few others had to make up as they went along.

Video technology and the mirror have this in common: that in reduplicating some fragment of the world, they introduce at least a very small spatial or temporal division into reality. The reflection is always at a greater or lesser distance—and if I try to take what I see in the mirror as a guide for my movements, I will always be in the paradoxical situation of trying to follow something that is following me.

In the 1970 performance Mirror Check, the performer (Jonas herself at the time, though during a night of performances at the Tate a different performer took her place)stands naked, systematically inspecting her body, inch by inch, using a small circular mirror. The audience never sees what she sees. In a way, we see more than she does, but what her eyes see is lost to us. We will never see enough of our world or ourselves.