Much indicates, indeed, that Diderot neither desired nor deemed possible a truly complete art form, even going so far as to argue that “a poet who finishes everything … turns his back on nature.”44 Even before Le Fils naturel, he had tempered his praise for the visual arts with the warning that too flawless a reproduction risked hindering the spectator’s imagination: “How is it possible that of the three arts that imitate nature, the one with the most arbitrary and least precise expression speaks the most intensely to the soul? Could it be that, showing objects less, it leaves more freedom to our imagination?”45 Such a warning must have seemed particularly pertinent to the theater, the sole art form with the capacity to show objects as they appear in reality—at once in space and in time. As we saw, it was this very capacity that appealed to early advocates of reenactments, for it strengthened their faith in the possibility of a transition from imitation to reality, as illustrated in the following, sequential praise of the theater: “It is no longer an image, it is a portrait; it is even more: it is the object itself, the original.”46 A performance of this type, insofar as it claims to present reality, rather than represent it, demands of its spectators nothing less than complete belief, thus restricting the exercise of their creative faculties. Sainte-Albine had embraced precisely this unimaginative response when he noted approvingly that only the theater required no “supplement” from its viewers.47 Diderot, however, condemns it, on the grounds that without imagination “one is neither a poet, nor a philosopher, nor a man of culture, nor a reasonable being, nor even a man.”48 Evidently, imagination consists for Diderot of a faculty with tremendous range, to such a degree, in fact, that he provides a vast array of definitions, reflecting the diversity of his interests (physiology, aesthetics, and sensationalist philosophy, to name only a few). Among these definitions, Margaret Gilman has identified several common traits, which taken together reveal a largely coherent vision of imagination as an active process of image combination, in contrast with memory, which Diderot defines as a purely reproductive and thus passive faculty.49 The principal attribute of imagination is therefore its creativity, as it brings forth unique productions, unlike even the objects that inspired them, solely by combining, rearranging, and augmenting preexisting sensory images.
Hence, if indefinite or unfinished works of art most effectively stimulate the imagination, as Diderot believed, it is because they stir in the spectators the desire to construct a complete picture from the fragment they perceive, a task requiring the exercise of the very intellectual operations specific to imagination—combination, rearrangement, and augmentation. Accordingly, Diderot, more than any other French critic of his time, was drawn to incompleteness, particularly in painting, where it served to offset the visual arts’ predisposition toward undue precision. In his Salons, he regularly praises the emotional impact of sketches,50 which he credits to the imaginative freedom they allow: “What attaches us so strongly to sketches is perhaps that, being indeterminate, they leave more freedom to our imagination, which sees in them anything it pleases.”51 In the presence of a sketch, the beholder works in concert with the artist to create as stirring a work of art as possible. For Diderot, art is at its most powerful when collaborative, if only because, as he observes in his description of a sketch by Greuze, “I know better than anyone how to move myself by the experience I have of my own heart.”52 Moreover, a spectator’s imaginative involvement heightens the emotional impact of a work of art because, while building upon the framework provided by the sketch, it creates an image that knows none of the formal limitations and conventions of art. In the words of Friedrich Melchior Grimm, Diderot’s friend and admirer, “the most sublime genius cannot execute as well as the most mediocre imagination; the latter creates and invents as it pleases, whereas art finds, in the execution of its thoughts, hurdles at every step.”53 For Grimm as for Diderot, the execution of an idea or image into a work of art requires a series of concessions to the formal restrictions of one’s art—a technical adaptation leading inevitably to a diminution of the image’s emotional impact. A sketch partly succeeds in eluding this process of attenuation because its indeterminacy alludes to a forceful image unspoiled by execution, thereby prompting its beholders to recreate it in their imaginations, the sole canvas where fantasy is truly unchecked by artistic technique.
As a result, Diderot concludes in his Salons that a sketch, unlike a finished painting, has the power to transmit the artist’s mental state without the alterations produced by reflection and artistic technique: “[A sketch] is the artist’s moment of fervor and heat, pure verve, unadulterated by the artifice that reflection adds to everything.”54 A sketch remains necessarily incomplete, because it originates from an emotion so sincere and overwhelming as to be only expressible in the manner the artist experiences it—suddenly, impulsively, and transiently. Accordingly, for Diderot, a sketch’s effectiveness as a creative catalyst derives less, as one might expect, from its spatial fragmentariness than it does from its temporal incompleteness. Indeed, a finished painting, a corner of which has been erased after being accidently covered in white paint, does not as a result become a sketch, because, in the absence of short, choppy strokes and other signs of precipitation, it fails to expose the movement of its own creation. By contrast, a blank in a true sketch is likely to be perceived as a space “in waiting,” rather than as a loss or as an accident, because the sketch as a whole cultivates in its beholders the sense that they are witnessing the coming into being of a work of art rather than simply its fixed and final form.
For Diderot, therefore, a sketch is to a painting what a reenactment is to classical theater. Indeed, a clear parallel exists between the incompleteness of a sketch and the suspension of Le Fils naturel. As Clairville describes it, a reenactment, like a sketch, arises from the experience (indeed, the reliving) of an emotion so intense that it expresses itself instantly and artlessly—notably through interrupted gestures and unarticulated accents that are analogous to the halted, uneven strokes of a sketch. Insofar as a reenactment serves as a medium for genuine emotions incompatible with artistic technique, it always risks leading, like a sketch, to its own suspension. Lastly and most significantly, a reenactment, again like a sketch, encourages its spectators to become participants by convincing them that they are beholding an improvised spectacle, subject to modification. To be sure, the theater always operates, in the words of Jean-Christophe Bailly, “as a fragile coming-into-being, not something that is held or holds itself whole, like a painting, nor something that unfolds purely and simply, like a film, but something unstable, only holding by a thread.”55 Nevertheless, many dramatic genres neither embrace nor even recognize this essential instability in the way that a reenactment does. To grow convinced of this, one need only look at classical tragedies and comedies, in which strict rules governing acting and playwriting, along with the weight of tradition and the existence of character types, enforced a relative constancy, both between distinct plays and between individual performances of a given play. By contrast, a reenactment, like a sketch, openly presents itself as incomplete