In the smoke-filled Gaumonts of yesteryear it was evident that a film was more than just a flickering image. It was also a beam of light, a beam that - as it fanned out from projector to screen - caught the rising particles of smoke and took visible 3D form: approximately, a four-sided pyramid. The audience's cigarettes revealed the physical basis of cinema's illusion. What's more, they created a spectacle that could be enjoyed in its own right.
But now suppose that the film you're watching is a very minimal and abstract show. It doesn't fill the whole of the screen's rectangle with colourful business. What you see is only a single thin line of bright white, with darkness all around. The light beam that projects this line will not have the form of a pyramid. It will be a mere plane, triangular in shape, with its apex at the projector, its base on the screen.
Introduce some smoke, and you'll see it - a thin, flat, sharp-edged dart of light, hovering in space, cutting through the dark. And if the bright line on screen should move or bend or grow, the projected sheet of light will evolve accordingly. Cinema can generate a form of immaterial, kinetic sculpture. These are the basics of the art of Anthony McCall.
He made the first of his "solid light installations" in 1973. The work was called Line Describing a Cone. It begins with the projector firing a narrow pencil of light that creates a single bright dot. The dot persists - and then begins slowly to extend itself into a line that traces a curving path on the screen, a regular curve, which at length becomes a quarter-circle, a semi-circle, and at last a full ring of bright light.
At the same time, of course, the projecting beam is also extending itself - at first into a narrow trowel-like form that eventually closes round to become the outer skin of a hollow cone. Vapour flowing from a smoke machine makes this cone of light visible. The full circle/cone takes 30 minutes to form. Line Describing a Cone is one of three McCall projections on view at the Serpentine Gallery.
McCall is over 60 now and this show is described as his first major London exhibition. His career has had a peculiar and encouraging shape, which the show's sub-title indicates: "Elements for a Retrospective, 1972-1979/ 2003". It's unusual for artists to stop. It's even more unusual for artists to stop and then - after a hiatus of two decades - to start again.
McCall began in the fluid, avant-garde scene of the 1970s, where conceptual art and performance overlapped happily with experimental film-making and "happenings" theatre. It is now a rather legendary period. With its revolutionary aspirations, rough-and-ready aesthetic, collective creativity, tiny audiences and tiny budgets it breathed an air of liberty unknown in our Tated, Saatchified, spectacle-rich and frantically careerist artworld.
In those great days, McCall was a member of the London Film-Makers Co-operative and lived with the US performance artist Carolee Schneemann, most famous for her act called Interior Scroll in which, naked, she pulled a long roll of paper out of her vagina. But in his mid-thirties, lack of income led McCall to give up art, and turn to working in graphic design. This he did for more than 20 years. Then, late in life, and largely on the basis of that projection piece from 1973, he decided to re-launch himself as an artist. It worked. Line Describing a Cone was acclaimed as a forgotten classic.
The Serpentine show has some of his other films from the 1970s, all very short and set in fields. A man digs a hole in the ground in a field, takes some of the earth, fills a cardboard box with it, puts the lid on the box, puts the box in the hole, buries it with the rest of the earth from the hole, and tamps down the turf, so that no trace remains. Some people move about a field each holding out a square of white linen that flutters in the breeze, a living moving geometrical abstraction. A field at night is dotted with a formation of separate fires laid out in a square.
These playful and gratuitous visual acts seem rather far in spirit from the impersonal process of Line Describing a Cone, which was made at the same time. But such contrasts are typical of the Seventies avant-garde, where an absurd kind of fun often alternated with rigorously methodical operations and provocative shock tactics.
Line Describing a Cone was conceived as a piece of anti-cinema, which would challenge the audience's habitual practice of sitting in rows and fixing their eyes on a moving 2D image on the screen. This was cinema that offered a 3D image in space, an image that the audience could both watch and physically participate in. But the effect was not - one gathers - originally intended to be beautiful, spectacular, magical or subtly mathematical.
When McCall returned to working in "solid light" in the 21st century, those aspects came to the fore. The two other, very recent pieces at the Serpentine are extremely elegant and complex light shows. Turning Under is a pas-de-deux for straight line and undulating wavy line, in which the two elements move and circle and intersect according to some elusive geometrical programme, while their planar beams go through a correspondingly intricate and convoluted manoeuvre in space. You and I, Horizontal III is still more elaborate, a panoramic piece for two projectors, side by side and precisely synched, in which an array of curves and straights perform a sequence of gradual and sudden developments.
The difference is partly technological. Line Describing a Cone was made as a simple stop-frame animation, the camera filming a white-on-black drawing, gradually revealed, rotated on a drawing pin. The recent ones are of course made on computer, which accountsfor their phenomenal complexity, as well as their perfect clarity of line and plane, their total control of coordinated movement - and (a downside) the fact that, if you look closely, the whole image breaks up into grid of little squares.
However, the essential pleasures of McCall's solid light installations remain fairly constant between 1973 and now. There's the pleasure of seeing something invisible - passing light - made visible. There's a nice feeling of projected light as touch, marking or stroking the surface it falls on. There's the way the mind stretches between 2D and 3D perception, as the flat pattern on the screen is "projected out" into clear solid forms, or (equally) as the screen pattern appears like a planar intersection cut through the solid forms. There's the way these forms in space, though so sharply defined, aren't really solid, but utterly penetrable, transparent, just marked-out sheets of space.
You can view them from every side, and from inside. You can stand with your head in the middle of the cone of light, say, and see its glowing walls from within. Meanwhile, there's all sorts of play between motion and stasis, and a heightened awareness of light itself as always in motion and directional. There's the interaction of light and smoke, the sharp and regular forms of the light made visible as they are passed through by the flowing, billowing, chaotic forms of the smoke.
And if some of the last two paragraphs was a little hard to comprehend, that's because McCall's light installations deal in spatial phenomena for which everyday language is not well adapted. Still, having tried to describe and convey these gracefully and transfixingly baffling experiences, there doesn't seem to be much to say about them. Good.
In contemporary art, optical and cognitive disorientation often has a spiritual agenda behind it - see the work of James Turrell, Anish Kapoor or Antony Gormley. We're to feel ourselves lost in the mysterious void of the cosmos. I can't detect anything like that in McCall's work. It seems to hold an entirely secular understanding of light, space and the human mind. It is what it is. Even though we may not quite get our heads round what we're looking at, the magic is all in plain sight. It makes no call for further commentary. All it asks is to be seen.
Anthony McCall, Serpentine Gallery, London W2 (020-7402 6075) to 3 February