The article

The results of these tests, ordered to settle a dispute over whether the yellowed painting would be enhanced or endangered by a restoration, are in. "Based on what we found, I would rule out any major work at this point," said Maurizio Seracini, the independent art diagnostician called in on the case.

Critics of the proposed restoration, which was to have begun last spring, see the decision as a moral victory and a personal vindication. More than 30 Renaissance scholars signed a petition just before the work was to begin, pleading that the painting, commissioned in 1481, was far too fragile to be overhauled.

"This is the first success we've had," said James Beck, a Columbia University professor and founder of ArtWatch International, a group that monitors restorations. He has spent 13 years crusading against the dangers of overzealous restoration, singling out projects like Leonardo's "Last Supper" and Michelangelo's Sistine Chapel. "I'm an old man who has been ostracized for taking a position that was unpopular," Mr. Beck, 71, said. "But now I feel I've done the right thing in Florence."

Leonardo Da Vinci's "The Adoration of the Magi."
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Maurizio Seracini working on "The Adoration." Some of his tests have to be made in complete darkness.
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The director of the Uffizi, Annamaria Petrioli Tofani, however, is just as convinced that the decision against the restoration is a colossal mistake. To her, it was a cowardly choice made by her boss, Antonio Paolucci, who oversees all the state museums of Tuscany, and with whom she has been feuding for some time.

"Paolucci received this threat from Jim Beck, so he decided to give up," she said.

Mr. Paolucci acknowledged the pressure. "It's not the right moment politically" to go forward, he said. After the controversial restoration of "The Last Supper," in Milan was completed in 1999, "restorations should be done in silence," he said. "We don't want an international fight over Leonardo." He insisted, though, that his decision was based solely on the test results.

Yet both sides cite Mr. Seracini. For Mr. Beck, his tests "show the risks outweigh the gains." For Ms. Petrioli, "they reveal that what we see now is not the real painting by Leonardo, because there are other layers" of paint added later, apparently in a masterly 17th-century renovation, and several coats of varnish, the most recent brushed on about 100 years ago.

"These prevent us from appreciating the real Leonardo," Ms. Petrioli said. "It is as if we were reading a poem where there were two words, then one lacking, two words, then one lacking."

Both are right, too. Mr. Seracini found no urgent reason to proceed with a restoration but did find a whole sketch pad of work by Leonardo under the paint, work that has already significantly altered understanding of the piece.

"It was like discovering a new, totally unknown work by Leonardo," said Mr. Seracini, who is a boyish 55. "I've tested 31 works by Raphael, and this is my third Leonardo. But among the 2,000 paintings I've worked on, this was the one with the most surprises. We unveiled a planet."

Mr. Seracini, a native Florentine, trained as an engineer, then went to medical school but left after three years when he ran out of money. While in college at the University of California at San Diego he also commuted to the University of California at Los Angeles to study Renaissance art under Carlo Pedretti, the Leonardo scholar.

Most of the equipment Mr. Seracini uses has been adapted from the medical field, and he thinks of himself as a doctor whose "patients are works of art." Using X-rays, infrared cameras and ultraviolet light, Mr. Seracini has gotten beneath the surface of the "Adoration" and seen through its layers of pigment. Often he works through the night because some of his instruments have to be used in total darkness.

Back in his office, a short walk across the Ponte Vecchio, he displayed some of the results from that work on several computer screens.

First, he showed photos of the painting as it is today, a fading image of the biblical story of the three kings visiting the Virgin Mary after the birth of Jesus. The figure of the Madonna is covered with a grayish coat of varnish, and the entire piece has an oxidized orange tint.

Then he showed pictures taken under ultraviolet light, which makes the brush strokes much more visible but also highlight layers of dirt so thick they block some of the figures entirely.

But images captured with an infrared camera reveal figures invisible to the naked eye. Here, it is possible to see men rebuilding a ruined structure - one man positioning a stone, another with a log on his shoulder - and it is these images, discovered in tests Mr. Seracini did on the painting some years ago, that have revised the understanding of the painting.

"This means the painting is about the reconstruction of a world in ruins, rather than just a view of the ruined world at the beginning of the Renaissance," as had been previously thought, Mr. Seracini said.

Mr. Pedretti, the Leonardo scholar, said: "This new interpretation is well accepted now, based on Seracini's earlier work. But what he has found recently gives us perfect knowledge of the painting. It's an extraordinary thing that's underneath there."

Several obscured faces in the crowd around the mother and child come into much sharper focus. Rocks appear under the Madonna's feet, and a beautiful woman materializes behind one of the magi. An elephant that had been completely covered by paint is exposed. And all of the expressions become much more vivid, most strikingly one of the magi, who looks lost in a devotional reverie.

Mr. Beck clearly worries that all the excitement about these details could be used to justify renovations.

But Mr. Seracini agrees that they should not. "We have to respect the history of the painting, not just the initial composition," he said. "It's our duty to know what the painting was in the beginning, but not to bring it back or try to cancel time."

For him, in any case, the important thing is not whether any one work is restored, but that decisions about such restorations are made more carefully than they have been, after scientific tests and an international debate on the findings.

"Nobody would dare send a patient to surgery without knowing the pathology," he argued. "Yet normally we are only called in to do a autopsy" after a restoration has been botched.

Even now, Mr. Seracini still has several months' work ahead of him on the "Adoration," assembling thousands of enlarged photos of the infrared, ultraviolet and X-ray versions of the painting into large mosaics. After that, he will present his final report to museum officials.

Meanwhile some minor corrective work will be done on the glued-together planks of wood that support the painting and have shifted over the centuries.

Then, Ms. Petrioli said sadly, "the painting will go back on the wall, exactly as it was when it was removed."