On Alberti's "sign": vision and composition in quattrocento painting - Leon Battista Alberti's commentary 'On Painting'

Medieval Latin handbooks on art also emphasize the schematic aspect of the crafted image. Paul Hills shows that these handbooks treat pictorial modeling as analogous to sculpting the picture plane. Dark lines indicating recession are called incisions, "a term taken over from gem carving or engraving on metal or glass." According to Hills, "the adoption of a term from carving suggests how closely painters conceived of their linear modeling with a dark tone as analogous to gouges in the surface: the modeling furrows on ivories offer a likely prototype."(19) Conversely, the projection at the center of each area is indicated by a white stripe called matizatura, which Hills convincingly interprets as luster rather than highlight, or the lightest tone of local color on an illuminated object. Like luster, Hills explains, white stripes of matizatura

obliterate . . . the local color; they do not blend with it at the edges. Their location does nothing to indicate a consistent direction of light and their dynamic mobility may even seem like a painter's attempt to capture the mobility of lustre - a mobility the painters would have noted on their models, antependia in metalwork and enamel.(20)

Hills's insightful analysis points to a conclusion that he does not sufficiently stress: incisions and luster are qualifies of the crafted picture plane, not of the depicted person or thing. If they serve to model the prototype, it is through reference to a shape, form, or figure that the artist has impressed as if in relief into the painting.

The discussion of dark lines and white stripes in the art manual De diversis artibus, written by a German monk named Theophilus, probably in the early twelfth century, strongly suggests that the shape, form, or figure of Latin medieval art is the same as the linear schema of Byzantine art.(21) Theophilus advises painters to designate (designare) with shadow

the eyebrows and eyes, the nostrils and mouth, the chin, the hollows around the nostrils and the temples, the lines of the forehead and neck, the curves of the face, the beards of young men, the joints [articulos] of the hands and feet, and all the parts which may be distinguished [distinguuntur] in the nude body. . . . [Conversely with luster (prima lumina)] you will illuminate [illuminabis] the eyebrows, the nose in its length and on each side above the openings of the nostrils [nasum in longitudine et super foramina narium ex utraque parte], the fine lines around the eyes, below the temples, above the chin, near the nostrils and on each side of the mouth, the upper forehead, between the wrinkles of the forehead - [but these only] sparingly, the neck in the middle, around the ears, the joints of the hands and the outside of the feet [ac articulos manuum et exterius pedum], and every rotundity in the middle of the hands, feet and arms [et omnem rotunditatem manuum et pedum et brachiorum in medio] .(22)

Like Byzantine iconophiles, Theophilus has the artist circumscribe the

namable parts of the prototype. Dark lines mark with shadow the divisions between these parts; white stripes indicate luster at their projecting centers. No attempt is made to show how the parts flow together on the surface of the represented body. These incisions and projections pertain directly to a linear schema inscribed on the painting and only indirectly, through this schema, to the prototype; they model the schema, not the prototype. Here, too, the primary unit of recognition is the prototype and its namable parts, not its surfaces.