Andre Malraux, writing in The Voices of Silence, observed that "every great painter has his secret, that is to say, the means of expression by which his genius usually avails itself." In the paintings of Georges de La Tour, Malraux explained, subtle modulations of red functioned as the characteristic instrument of the painter's attenuated yet evocative colorism. More generally, Malraux was trying to suggest that the old masters, as a rule, grounded their accomplishment in technical procedures, formulas, and special working methods at once appropriate and unique to their purposes. Of course, painters forged their secrets out of a delimited array of overlapping practices. La Tour's palette, Malraux noted, might seem to have resembled that of Caravaggio. And yet the works of the two artists were "utterly different" and could never be mistaken for one another.1 The painter's secret, then, was not transferable. Born from the spirit, it served as the material signature of the artist's creation.
This exalted conception of the role played by technical procedures in artistic creation is as common as it is misleading. Across the history of art, painters have indeed worried that their secrets could be stolen or, if imparted to students, studio assistants, or colleagues, shared or traded. The artisanal workshops of the Middle Ages and Renaissance offer countless examples of painters who declined to reveal their working methods. That much remained true for the eighteenth century. Denis Diderot, speaking of the "totally idiosyncratic" technique of Jean-Simeon Chardin, reported that no one he knew had seen the painter at work.2 As it happens, Diderot deplored artisanal secrecy; in the Encyclopedie, he called on the state to plant agents, posed as apprentices, in the studios of craftsmen: "there are few secrets that one cannot uncover by this method."3 It would be wrong, however, to conclude that artists' secrets were confined to the craftsman's workshop. Nineteenth-century France, for example, might seem to offer no natural home for artisanal culture. And yet here we could single out Alexandre-Gabriel Decamps, a leading Romantic painter whose bravura technical procedures were the subject of much speculation. The critic Charles Blanc compared Decamps's studio to an alchemist's laboratory, the site of occult transmutations of matter hidden from the eyes of curious colleagues. Still others likened Decamps's pictorial execution to the virtuoso violin playing of his contemporary Niccolo Paganini, who was himself held to guard his secrets jealously. We could also point, later in the century, to the case of Georges Seurat, another outstanding inventor who painted in solitude. So great was Seurat's paranoia regarding the dissemination of his method that he was disinclined to exhibit his pictures and charged his followers with theft and betrayal.4 Camille Pissarro, for one, was appalled by Seurat's attitude: "I recognize no secret in painting other than that of the artist's temperament, which is not easily swiped!"5
Surely Pissarro was right: nothing one painter stole from another could make him a great artist. Then as now, technical procedures were less the source than the instrument of invention. Yet many painters, to judge from stories told about them, have declined to endorse this idealizing conception. Granted, those stories often turn out to be just that-stories. The notorious secrecy of artists forms part of the conventionalized fabric of artistic biography, an ancient and enduring topos rehearsed and renewed into the modern age. Without further explanation, however, the topos argument only deepens the mystery. Why did painters feel obliged to conceal their technical procedures? Why did their biographers so often evoke such practices, to the point of fabrication? Why did this predilection for secrecy, commonly associated with artisanal culture, survive into the nineteenth century and beyond-even as artisanal practices declined? …