An art sale was about to take place at the respected Christie's auction house in Manhattan, only something seemed to be missing—namely, a piece of art. To help out on that, the auctioneer pointed at a wall: From the back of the room, it looked white and blank, and even from the front one could make out only faint, crisscrossing lines. But this was no time for finicky carping, let alone raising a hand for a question. About 80 seconds into the bidding, art dealer David McKee had it for $26,400—though just what it was he had, to Philistines in such matters, was less than clear.

McKee had purchased the first intangible work of conceptual art ever sold at auction in the U.S., meaning that he bought simply the right to execute an idea by artist Sol LeWitt—nothing more. McKee's actual purchase is a typed certificate specifying that the work be drawn in "black pencil" and bearing this instruction: "Ten thousand lines about ten inches (25 cm) long, covering the wall evenly." This formula was used in drawing the art work on Christie's wall, but only as an example, and the day after the auction it was destroyed to preserve the value of the original—which is the formula, remember. That now belongs to McKee, who can have the 10,000 lines re-created on any wall of his choice. Of course, so can you, but you wouldn't have the real thing.

Perhaps it is time for a bit of art history. Since 1968, artist Sol LeWitt has been a leader of the conceptual movement, which seeks to broaden the parameters of art. By selling instructions for works of art rather than the works themselves, he tries to show that the idea is more important than the object. Whatever one thinks of that, LeWitt believes in it and has been successful at it. His instructions have been bought by such lofty institutions as the Museum of Modern Art. The work McKee now owns was sold by the Gilman Paper Company, which purchased it for about $20,000 in 1976 and has now destroyed its version too. "It's an important work to me because the idea behind it is so basic," says LeWitt, 58. "In the early '70s, a lot of people were interested in the idea that art didn't have to be done by people with a great deal of training. I was striving for that."

Still, the old concept of owning an original—or in this case, the latest rendering of an original—survives. Says LeWitt's dealer John Weber, "Ever since sculpture was cast in Roman times, you could pull another cast of a work. But it isn't important that a copy can be done. The import of a work is that it is unique to an artist." David Higginbotham, a writer and filmmaker who has drawn many of LeWitt's works, including Christie's wall, finds the process deceptively tricky. Spacing the lines and counting to 10,000 took about 11 hours of concentration, especially with busybodies at Christie's asking what the heck he was doing.

McKee hasn't said who will execute LeWitt's wall painting this time, but he hints he will display it in a public space. He doesn't seem concerned about the possibility that it might get stolen.