Hoodwinked by Hockney?
David G. Stork
As one of the two scientists at the December Art and Optics symposium to analyze David Hockney’s bold theory (both rejecting it), I read David L. Sweet’s surprising review of Secret Knowledge [April, 2002] with great interest—surprising because his was the first I’ve read to find Hockney persuasive. Sweet seems to excuse him of the obligation to frame a coherent argument since Hockney writes “free of the professional constraints of the traditional scholar,” but if we are to judge the theory, such constraints must then pass to reviewers; it is here that Sweet does not quite prove up to the task.
Sweet does not point out that murals, ceilings, self-portraits, moving objects and non-existent objects (e.g., dragons) cannot be recorded by Hockney’s mirror projection method; that because Caravaggio worked in dark cellars by artificial light (as Hockney [p. 241], seventeenth-century biographers, and most modern art historians attest) he must have used over 1000 candles at a time; and that virtually all brushstrokes visible in Renaissance paintings or hidden beneath (revealed by modern infra-red photography) are “downward” thus contradicting the theory that these paintings were executed at least in part upside-down.
Sweet notes the slight anamorphoses that occur in some paintings, but these can arise when artists paint with their canvases at slight angles. Indeed, the first deliberate anamorphic drawings, in Leonardo’s Codex Atlanticus, were almost surely created this way. Likewise slight perspective inconsistencies such as in the coin box in Holbein’s portrait Georg Gisze [p. 63] can be explained naturally by the artist moving forward to get a better view. Similar explanations apply to paintings displaying the “collagist perspective” from northern Europe.
Sweet mentions that concave mirrors were available in the fifteenth century but not that we lack any evidence for the long-focal-length mirrors demanded by the theory. Moreover, while simple by today’s standards, in 1430 the manufacturing, testing and projecting of images with such mirrors would have represented the most sophisticated optical engineering on the planet—their “Hubble telescope.” While perspective constructions, familiar to every schoolchild with a ruler and pencil, consumed some of the greatest mathematical, architectural and artistic minds of the fifteenth century and led to numerous scholarly treatises, despite historical records of all manner of obscure optical and drawing devices—from anamorphic mirrors and the bacolo of Euclid to zoetropes and zograscopes—there is no corroboratory evidence for the required concave mirrors in their hypothesized projection use—not a single artifact or passing mention by a scientist, portrait subject, patron, guildsman, Inquisitor, or of course artist. The claim that trade secrecy or the Inquisition suppressed the “secret knowledge” is extremely implausible, an extraordinary argument I have never seen applied to any analogous case involving hundreds of independent or rivalrous “co-conspirators” and tens of thousands of observers over centuries.
Hockney’s sumptuous book hopes to persuade by visual example but occasionally backfires. The portraits by Dürer and Hals that Sweet reproduces show that Hockney’s “opticality” may be due to surfaces, shading and subtleties in color rather than contour; rendering surfaces is never aided by tracing outlines in the manner Hockney demonstrates in his book. And if you try to paint directly under optical projections, rendering such surfaces is impeded significantly. Hockney claims [p. 128] that de la Tour’s St. Joseph the Carpenter—which shows a single candle throwing light and shadows right, left, up and down—was actually painted under bright direct sunlight somehow shining in horizontally from the left and then from the right. I wonder if Sweet accepts this claim.
The central problem with Mr. Hockney’s book, and Sweet’s review, is that alternate explanations are either overlooked or dismissed without adequate consideration; they are never adequately disposed of. Consider a few non-optical factors that might yield “opticality” in the early Renaissance: Masolino and van Eyck were experimenting with oil paint and its enhanced contrast and saturation; geometrical perspective gave rise to a new interest in realism; trading between the Medici and the Burgundian Court increased the demand for accurate portraits; the Popes returned to Rome from Avignon and began a renovation of Roman art and architecture that opened their eyes to the seen physical world rather than the conceived spiritual one; spectacles and magnifying glasses first became popular, allowing myopic artists to see with a new clarity (an “optical” explanation quite distinct from Hockney’s). None of these rely on the world’s most complicated optical system of the time which has no corroborating evidence.
It falls to Mr. Hockney and his supporters to dispose of traditional explanations and the numerous non-optical explanations for detailed effects in individual paintings. In being persuaded by Hockney, Sweet either doesn’t realize that they have failed to do this or doesn’t care.
[A slightly altered version of the letter was edited by Art in America, their final version not available on the web]