Secret Knowledge Rediscovering the Lost Techniques of the Old Masters by David Hockney Viking, 296 pp., $60 WHEN David Hockney shared his hunches about optics and art history with the New Yorker nearly two years ago --which reported them with some (but not enough) skepticism--did he imagine the uproar or the opportunities he would provoke? In the wake of that New Yorker story announcing Hockney's thesis that the Old Masters painted with help from secret technology, there came a flood of offers to help develop his conspiracy theories. The BBC let him expound in a seventy-five-minute documentary. Hockney and his assistants prepared a coffee-table book tie-in, entitled "Secret Knowledge" (rights for which were shopped to American publishers at an asking price of $600,000), a package that Hockney has been promoting in recent months with interviews on radio, television, and in newspapers around the world. Only cicerones of the order of Sir Kenneth Clarke, Robert Hughes, and Sister Wendy have commanded media exposure on this scale. Finally, this December--in a kind of apotheosis normally reserved for such monuments of art scholarship as Panofsky or Gombrich--a two-day symposium was organized in Hockney's honor at New York University's Institute of the Humanities. Convened to discuss his self-proclaimed discoveries were some of the most illustrious art historians: Svetlana Alpers, Rosalind Krauss, and Michael Fried. Joining them were Susan Sontag, painters Chuck Close and Philip Pearlstein, and the former director of the Getty Museum, John Walsh, among others. Serious people, serious money, serious respect. But maybe Hockney isn't surprised at what's happened. As an Englishman residing since the 1960s in Los Angeles, he must have observed that celebrities are often granted improbable liberties to advance pet causes, however outrageous; and that the media, with an insatiable hunger for controversy, are megaphones for all kinds of glamorous amateurs and nuts, provided they're sufficiently well-connected. Hockney is not a nut. One of the few high-profile contemporary artists to describe for a general public how he looks at the work of other artists, he has an alert and curious mind. He enjoys thinking through the technical problems of making and seeing art. A 1990 documentary in which he analyzed a seventeenth-century Chinese scroll is marked by acute observations about a tradition far removed from his own. Still, after looking at his book and the BBC film, and especially after attending the NYU conference where his slipshod arguments and naivet were held up to the bright light of history and logic, I find it hard not to picture Hockney alongside those literary sleuths who periodically since the mid-nineteenth century have uncovered "proof" that Shakespeare didn't write Shakespeare's plays and poems. Of course, it's not foolish to wonder about the anomalies that are sometimes visible in Western paintings. But Hockney shows all the signs of being a coddled celebrity whose every apercu is treated reverently by those flattered to earn his attention. He seems to have no one strong or trusted enough who could sift his intriguing insights from his banalities, the thoughtful guesses from the harebrained. Proud to be a working artist rather than an art historian shuttered in a library, he suffers from an overwhelming belief in his own eye. As in his earlier books on photography, he seems oblivious to earlier scholarship. It would be thrilling to report that the plucky sixty-four-year-old autodidact has uncovered what the Ph.D'd professionals have for decades overlooked. But, about the Old Masters, it turns out Hockney is largely wrong. AS HE WRITES in "Secret Knowledge," Hockney began his journey at a London show of Ingres's drawings that left him "awestruck." The lines seemed so tiny and "uncannily 'accurate'" that he was sure, from his own experience, they could not have been "eyeballed," by which he means drawn freehand. (Sontag characterized this logic as: "Because I can't do it, they couldn't have done it.") More, the confidence of Ingres's hand reminded Hockney of an Andy Warhol drawing made from a projected photograph. From this he decided Ingres must have used an early projection technique called camera lucida to draw portraits. Suddenly Hockney began to notice correspondences everywhere. A host of classic painters came under his suspicion for using lenses and mirrors to achieve their effects. His assistants photocopied works from the canon of art history textbooks and hung them on the wall of his studio, where Hockney eyeballed them to identify paintings with an "optical look." "Secret Knowledge" bears the scars of this method. Hastily assembled for the market, it is divided into three unintegrated parts: a large group of famous paintings reproduced with a few paragraphs of commentary by Hockney; historical texts about optics through the centuries; and sixty-two pages of back-and-forth faxes between the artist and various art historians and scientists he hoped to enlist for his cause. The case for the use of optical devices by the Old Masters begins with the observation that mirrors and lenses were widespread in Europe as early as the fourteenth century, with artists learning about the physics of light as Renaissance scholars translated the writings of ancient Greeks and medieval Arabs. Over the following centuries, many visual inventions--particularly camera lucida and camera obscura--applied this new science, both to improve observation and as devices of wonder, until 1839 when photography trumped them all with its chemically fixed illusions. There is nothing controversial about any of this. Artists have never tried to hide a familiarity with lenses or mirrors. Jan Van Eyck's "The Arnolfini Wedding" (1434) prominently features a convex mirror. Leonardo da Vinci investigated the science of optics in his notebooks. In the sixteenth century several Italian mannerists demonstrated their bravura technique by painting objects or figures reflected by mirrors, as in Parmigianino's "Self Portrait in a Convex Mirror" or Savoldo's "Portrait of a Man." Several artists' manuals from the period diagram the camera obscura, a box with a hole that reflects the lighted scene in front of it up onto a plate for tracing. But Hockney leaps from these facts to the claim that European painters could not have achieved their celebrated precision of detail, grace of line, or three-dimensional realism without these optical aids. Only the application of optical devices explains the new connectedness of space and figures that historians have long noted appeared in Florentine art around 1420. The development of single-point perspective and oil paint were, according to the Hockney theory, comparatively minor. Only the secret trick of lenses and mirrors accounts for the special skills of Rubens, Caravaggio, or Vermeer. As several of the NYU panelists pointed out, there is no written proof for any of this. Leonardo's notebooks never mention a lens being used to project an image for drawing. Odd, that an artist so famously curious about technology, and without any of our Romantic qualms about applying it to art-making, would fail to cite such a device or the principles behind it. Odder still, that the legions of painters who copied his innovations and studied his techniques over the centuries never knew this secret either. HOCKNEY and his supporters hope to steer around the enormous lacunae in the historical record with various dodges. They claim that knowledge of image-projectors was either lost, or kept hidden as a kind of trade secret, or suppressed by everyone's favorite heavy, the Catholic Church. Hockney's explanations for why so much of the record is missing require a massive "X-Files" cover-up. The problem only becomes worse when he analyzes Old Master paintings themselves. Hockney and his chief ally, Charles Falco, a professor of physics at the University of Arizona, believe that even if painters could never admit they relied on visual technology, one can nonetheless identify the telltale signs in what Hockney calls the "optical look." So, in Lorenzo Lotto's "Husband and Wife" (1543), Falco finds in an oriental carpet both a blur and a "correction" of perspective as the pattern recedes away from the viewer. This can only mean, he argues, that the painter refocused an optical device. Puzzling as this detail is, it requires--as do other Falco examples--that the artist moved or "bumped" the lens for the evidence to fit. When Hockney tests his theories with his own hand, as when he tries to duplicate a Van Eyck and a Caravaggio in the BBC documentary using a lens fitted into a dark tent, the results are even less convincing. On location in Bruges, he singles out the chandelier in "The Arnolfini Wedding" as impossible to eyeball and proves this with a crude freehand rendition. It's true that we see how clear the chandelier's outline becomes when projected onto canvas by a lens inside a dark tent. But Hockney never moves from this to show us how well he could paint a Van Eyck using this secret knowledge; Hockney can't draw it freehand and so would need to trace a projection, but how exactly does that demonstrate what Van Eyck did? Hockney's attempt to stage-manage a version of Caravaggio's "Card Players" is less dishonest but just as farcical. Painting with optics by candlelight doesn't look any easier than freehand. THIS IS PERHAPS the highest hurdle faced by Hockney. If he's right, then most of the masterpieces collected in his book were originally painted upside down and reversed. As David Stork of Stanford University noted, this is an extremely awkward way to view and paint something--and if so many Old Masters took up the technique for so long, wouldn't some restorer or curator have noticed the brush-strokes in Van Eyck and Caravaggio and Ingres going up instead of down? Indeed, as Richard Wollheim added, shouldn't the use of these optical devices be even more apparent in the work of third-raters than in, say, Rubens? About the only good news Hockney received was from Samuel Edgerton of Williams College, who, forty years ago, conducted an experiment by drawing the Florentine Baptistry in perspective using a flat mirror. It's conceivable Brunelleschi had such help in 1425 when he astounded his contemporaries by performing a similar feat. Unaware of Edgerton's work, Hockney repeats the trick with a lens. Both examples offer tantalizing clues that, at least for large stationary objects in sunlight, a mirror or lens can aid the drawing of complex lines in perspective. Part of the problem is that Hockney seems never to have decided exactly what "opticality" is. Is it the rich three-dimensionality or the finely traced lines that constitutes the "photographic look" in European art around 1420? We don't need optical devices to account for three-dimensionality; the new mathematics of perspective and chiaroscuro better explain the fifteenth-century breakthroughs, which is what writers since Vasari in 1568 have believed. In fact, devices to help with tracing won't take an artist very far. Even the camera obscura, suspected for decades as being behind the blurs and tiny white circles in certain areas of Vermeer's canvases, would be impractical for constructing a large demonstration piece like "The Art of Painting." Such technology, even if used in places, doesn't lead us to a deeper understanding of Vermeer's hand and art. AT THE NYU symposium, Susan Sontag charged Hockney with being a spokesman for a "Warholization of art." That isn't entirely fair. Unlike Warhol, Hockney reveres the Old Masters and the art of painting. And his rejection of academic orthodoxies is brave. Hockney seems, at last, an innocent rather than a cynic. Looking for any faint confirmation of the Hockney hypotheses, Charles Falco seized on recent headlines that Thomas Eakins in the 1870s and 1880s traced from photographs. The evidence is sound and newsworthy. For the first time, a nineteenth-century painter has been caught collaborating hand-in-glove with the insidious machine. A paper by Nica Gunman, a conservator from the Philadelphia Museum of Art, suggested why Eakins kept this a secret: He had been extravagantly praised by a critic for a composition he knew was traced from a photograph; shame secured his silence. But the Eakins evidence cuts both ways. Several of his celebrated early canvases, including "Max Schmitt in a Single Scull," from 1871, were painted without a camera, as his many preparatory drawings prove. One could hardly ask for a more "optical" painting, and yet we know it was rigorously "eyeballed" with highly technical freehand sketches. Schooled in the Beaux-Arts tradition, Eakins didn't need a lens to draw with remarkable skill. Like Ingres and hundreds before him--and too few after--he didn't need smoke and mirrors. He was just another talented, well-trained, hard-working artist who knew how to draw. Richard B. Woodward is a critic in New York. He has written extensively about art and photography and taught at Columbia University's Graduate School of the Arts.