Darkness is pressing down on the appreciation of art, and both historians and scientists are to blame. Look at these examples:

In his new book Becoming Mona Lisa: The Making of a Global Icon, Donald Sassoon says that the modern popularity of the portrait's mysterious smile is the result of constant discussion about it, which makes Sassoon part of the problem. In writing about the "enigmatic smile," he keeps our focus on it, as if that were all the painting is about. But more about that in a moment.

Last year, neuroscientist Margaret Livingston said in a New York Times story that the smile seems fleeting because of the way our eyes and brains compute light and dark. If you're looking at the eyes with peripheral vision, she said, you pick up shadows from the cheeks that suggest a smile. But there is no such suggestion if you look directly at the mouth—which is as inconsequential as saying that if you look at an Impressionist painting too closely, all you see are paint smears.

Pooh-poohing the Livingston theory—and all others, for that matter—is Frederico Zeri, art history professor at Catholic University in Milan. In his book Behind the Image, he concludes that the smile is simply the effect of innumerable coats of varnish and dirt beneath the surface and that if the painting were cleaned, the mystery of Mona would disappear.

In 1999, Carlo Pedretti, director of the Armand Hammer Center for Leonardo Studies at the University of California, announced that all of Leonardo’s paintings were based on sculpture. He got this from Renaissance sculptor Benvenuto Cellini, who wrote that Leonardo sculpted clay models of his subjects before painting them. It’s odd that Pedretti would cite the words of Cellini, who was barely 15 years old when Leonardo resettled in France, away from where Cellini grew up, and not cite Leonardo, who wrote: "The lines of perspective of sculptures do not seem in any way true.… They can represent neither mists, nor dull weather, nor an infinite number of things…."

In 1996, in historical fiction, Rina De' Firenze suggested that the model for Mona Lisa was Leonardo's mother, Caterina. Why? Just a premonition, said the author—that and repeated visions of the artist's mother urging her to tell this to the world. No less silly is the theory of Dr. Lillian Schwartz of Bell Labs, a pioneer in computer graphics and computer art. She said that Mona is really Leonardo. By digitizing the features of both Leonardo's face and Mona's and merging them, she said, they line up. I feel a "so what?" coming on. How about you? I mean, if the smile in the portrait is good for anything, it's not because of a likeness to one person over another.

In 1959, Dr Kenneth D. Keele wrote in a medical journal that Mona was pregnant. How could he tell? The maternal calm of her smile, dummy.

Lady with an Ermine

Okay, let's get into it. You want to talk about that smart-ass little grin that never reaches Mona's eyes, that starts at the edge of her mouth, flickers and then dies, as if she decided to unsmile? To hear historian Henrik Willem Van Loon tell it in his book The Arts, her mouth is firmly set that way, rendering her strand-like lips indistinct as they merge into soft shadow because Leonardo didn't paint lips very well. Van Loon points to the same mouths in Leonardo's other portraits of women, Madonna and Child with St. Anne and Lady with an Ermine. In fact, all of his likenesses of women show the same features: heavy lids, pointed chin and balanced face, which suggest these were his ideals. Van Loon also said that the so-called smile can be seen in numerous ancient sculptures, which he contends is due to the same thing that plagued Leonardo: an inability to render mouths.

So, you ask, how can such a gifted draftsman have trouble with mouths? Van Loon has a ready answer. There's a big difference between drawing and painting, he says—that and the fact that Leonardo was not a disciplined painter. He seldom finished a picture, which accounts for the paltry number he left behind.

You can talk about Mona Lisa as a portrait all you want. But it's less a likeness and more a landscape, and no one in the art-hype business seems to notice that. Just look in the distance, and you'll see the sort of place that would make a Martian feel at home: rocks, rocks and more rocks. Beyond the scrim of dewy-edged Mona is alpine scenery cloaked in a velvety mist, and, if you ask me, it’s more haunting than she is.

Virgin of the Rocks

Leonardo gets it so right, you can almost smell the pungent river air. He painted this same backdrop in his other figure paintings, such as The Last Supper and Virgin of the Rocks. The rugged terrain is said to be the view of his hometown, Vinci, where the River Arno enters a gorge. His first known drawing was of the Arno landscape. Apparently, then, it was his field of dreams, not Mona.

So here's this quiet, oval face like stone, and it's just one of many stones that roar up from a faraway river. Her arms show the way. Folded tight as a gate, they are an entry to what lies beyond.

What do historians have to say when they actually get around to mentioning the landscape in Mona Lisa? In 2000, Carlo Starnazzi, a University of Florence paleontologist, told the Italian media that the rocky mountains in the background of Leonardo da Vinci's St. Anne, Madonna and Child are not a product of the painter's imagination but, rather, a direct copy of a region in the Tuscan Appennines known as the Balze. This is the same thing Starnazzi said about Mona Lisa some five years earlier—that the misty lake, jagged mountains and winding river behind

Leonardo's Mona are copies of a landscape in eastern Tuscany.

But, hey, so what? Does it matter to the eye that the waterway to the left is Lake Chiana, the winding waterway to the right is a canal that links the lake with the Arno River, the bridge is the medieval Burgiano Bridge and the mountains are Tuscany hills?

And why should we believe that an artist who can invent flying machines had to copy his subject in order to paint it? Leonardo seems to answer this in his Treatise on Painting: "If the painter wants to survey vast stretches of the country... he has it first in his mind and then in his hands.'' Painting is "una cosa mentale,'' a mental thing, he said. That said, it's hard to picture him setting up his easel in the Tuscany grassland to render the background in the portrait.

And because the details in this background disappear in the misty atmosphere, clearly Leonardo wanted viewers to see more than geography. He was not a naturalist. He painted mood, the undefined and the ambiguous. He used sfumato technique (blurring edges), as if he breathed the paint rather than brushed it. In Mona Lisa, he painted the land that he loved. And by the romantic air of mist, he seemed to want us to love it, too.

No such luck. The lights are fading, and the game is lost. Historians and scientists are getting in the way. Down in front, I say. You're spoiling the view.