Olafur Eliasson.

When Olafur Eliasson installed Your Sun Machine, 1997, at the Marc Foxx Gallery in Los Angeles, he added nothing to the space (at least nothing that wasn't in some sense already them). If anything, he subtracted from it, cutting a hole in the roof and letting the dazzling California sunlight flood in. Rematerialized as a vibrating patch on the floor, the distant celestial body became physically present; you could see it move. But Your Sun Machine was not just an artwork about the fiery body at the center of the solar system; it was also a piece about you. Things out there may appear to be moving, but, of course, it's the other way around; it's your own activities that make things appear as they do. The sun floats across the gallery floor because you yourself are traveling across the universe at an incredible speed, standing on this tiny planet of yours. Or had you forgotten that?

Eliasson's work depends as much on the position of the viewer as on light, heat, and moisture. Beauty, 1993, a key work the Danish-educated artist has recreated in several versions, defines the basic parameters that recur from installation to installation: an emphasis on perception and the viewer's active involvement in the process. Tiny drops sprinkle down from a perforated hose, creating a liquid curtain; a lamp sends rays of light through the water to produce a rainbow in the room.

The overtness of the technical setup is typical of Eliasson's art. Unlike the work of others who deal with light and perception (James Turrell being the most obvious point of comparison), there is no concealment of how the effects are produced. When you enter Beauty, the hose and the electric light are immediately visible. The work has the evasive quality of quickly shifting weather (take one step in either direction, and the whole thing's gone, like a gentle breeze or a reflection of sunlight off a passing vehicle). There are no secrets, just a fascinating optical phenomenon to be hold. Instead of being tempted to look for some veiled gadgetry, the viewer is thus confronted with the thing itself: the fact that light and water in combination produce color.

Phenomenology is one of those terms so variously abused in the discourse of contemporary art that they usually don't mean much of anything. It seems to me, however, that Eliasson's work could be said to represent a phenomenological approach in a stricter sense of the word. Kant's "Copernican revolution," further carried out by Edmund Husserl, insists on the active role of the subject for all experience and, ultimately, for the very concept of reality. All possible experience of the world depends on an experiencing subject, even when the object in question is understood as independent of the perceiving mind. Eliasson takes great care to make the active role of the viewer apparent. Even his titles suggest that the works are part of or even a product of the beholder's conscious life. Your Sun Machine, Your Strange Certainty Still Kept, 1996, and Your Compound Eye, 1996, belong to the person seeing them.

One may get the impression that Eliasson's art is all about nature, and more precisely about certain powerful natural phenomena of his native Iceland: wind, water, light, and fire. However, what needs to be emphasized is that the entirely new sensations his installations create are not natural, if "natural" is meant in the sense that experience has been purified of all artificial ingredients. If there is "purification" here, it's an effect of some mechanical process, as in The Curious Garden, 1997, in which one room of the Basel Kunsthalle was filled only with light. As the light was restricted to the yellow spectrum, however, the entire space was bathed in a lemony glow.

Although the focus on perception in Eliasson's work, in an uncertain era of new technologies and mediated subjectivity, is certainly visionary (as Jonathan Crary suggests in "Visionary Events," the catalogue essay for the Basel show) and is influenced by utopian minds such as Buckminster Fuller, there is nothing particularly futuristic or radically high-tech about his projects. The mechanical quality of perception would thus not be something that pertains only to today's situation, but is fundamental to human experience as such. In fact, Eliasson's works cannot be grasped in terms of a distinction between the mechanical and the biological. "Instead," Crary contends, "a nature/culture duality is dissolved within a single field in which machine and organism are not separable."

Neither nature nor the machine but the perceiving subject's relation to its heterogeneous environment: this would seem to be Eliasson's recurring theme. Is there any resolution to these phenomenological inquiries? Perhaps the artist would agree with Ludwig Wittgenstein that there is no such thing as phenomenology, only phenomenological problems. That's why the investigation must be ongoing; each problem demands its own forms of attention. So while some of Eliasson's inquiries have a spectacular quality, like By means of a sudden intuitive realization, 1996, where a jet of water illuminated by a strobe appears frozen into a series of solid bodies, others may be as simple as a huge amount of water (over five gallons per second) flowing down a street in Johannesburg or a row of minimalistic ice blocks slowly melting on the lawn of a Paris suburb. In these works, what Eliasson sacrifices in terms of definitive conclusions to his phenomenological queries is more than made up in the poetry of his gesture.

Daniel Birnbaum is a Stockholm-based writer and critic who contributes regularly to Artforum.