Sight unseen: vision and perception in Leonardo's Madonnas: in the first of two articles on Leonardo da Vinci, Larry J. Feinberg explains how the artist's interest in the way the eyes work influenced his realistic depictions of the Christ Child as a baby learning to see

Apollo, July, 2004 by Larry J. Feinberg

In recent years a number of scholarly studies have investigated and elucidated the complex intersection of Leonardo da Vinci's art with his other intellectual pursuits. (1) Understandably, these inquiries have concentrated primarily on Leonardo's notebooks and on his major religious compositions. Somewhat overlooked have been ways in which Leonardo's scientific and literary interests, such as those in optics and visual puns, informed a few of his smaller religious works, particularly his paintings of the Virgin and Child.

Careful examination of two of Leonardo's early compositions, the Madonna with the Carnation, of about 1475-78, in the Alte Pinakothek, Munich (Figs. 1 and 2), and the Benois Madonna, of about 1478-80, in the Hermitage, St Petersburg (Fig. 3), reveals his nascent interest in the physiology of vision and of perception--subjects that would, a decade or so later, become central to his research. The awkward naturalism of the anatomy and movement of the babies in the two works, and in the preliminary studies for them, has always been noted, as has Leonardo's evident observation of actual infants. But only brief, bemused reference has been made to the visual and psychological ungainliness of the Christ Child in the Munich painting and of the tentative actions of his counterpart in the Hermitage work. An advocate of experience over theory, Leonardo was determined to record with accuracy what he saw, even though his limited comprehension of the operations of sight could not account for the behaviour of the very young models he studied for the two pictures. In the Munich painting, the artist has rendered the child, eyes straying and unfocused, reaching almost blindly for the Virgin's carnation. In what can almost be regarded as a further elaboration on the activities of the Munich infant, Leonardo portrays the older child in the Benois Madonna as gamely trying to focus his eyes on a sprig of flowers, as he pulls his mother's hand toward him.

[FIGURES 1-3 OMITTED]

Leonardo's sensitive observations of the children's actions resulted in touching and credible portrayals of familial interaction. But for the painter these observations also created a slight conundrum. For no one in the later fifteenth century, including Leonardo, understood the workings of the lenses of the eyes and, therefore, truly comprehended the behaviour of an infant struggling with his eye-hand coordination. In fact, full knowledge of the function of the eyes' lenses would only be attained in the mid-nineteenth century, with the researches of the German psychophysicist H.L.F. von Helmholtz. In his Physiological Optics (about 1856-66), Helmholtz explained for the first time exactly how the human eye focuses, as the ciliary muscles adjust the curvature of the anterior surface of the lens. (2) Moreover, he pointed out how the pupil contracts (limiting light and vision) when the lens accommodates for near objects and when there is a strong convergence of the two eyes--facts no less pertinent to Leonardo's depiction of the child in the Benois Madonna. (3)

Since Helmholtz's discoveries, much more has come to be known about the physiology of sight and the neurological development of the brain and eyes of an infant. Relatively recent neuroscientific studies have shown that a baby's ability to focus has less to do with the development of motor skills than with its body's natural production of the chemical myelin, which is necessary for the conduction of nerve impulses within the brain and to the eye. (4) A child usually does not develop the myelinated nerve tracks (axons) that are required for 20/20 visual acuity until the age of eighteen to twenty-four months. (5)

Of additional relevance to Leonardo's infants is the ongoing research of neurological scientists that is beginning to reveal how the brain processes visual information. (6) This work has determined that separate cortical areas of the brain are responsive to different kinds of visual information--that is, one area of the cerebral cortex is sensitive to the spatial orientation and motion of lines, another acts as the principal receptor for colour, a third area is the main analyser of form, another serves as the chief organiser and analyser of colour, and a fifth registers the movement of objects. (7) Such a complicated, highly-integrated, and interactive system, known as 'modular organisation' (in reference to the individual and distinct modules or subsystems of the brain), requires substantial neurological wiring to function properly. An infant's inchoate neurological state does not permit the full operation of this system. (8) Further, modular organisation also involves the subtle processing of incoming visual data through the filter of experience and memory, in which infants are limited as well. (9)

Not only was such information about neurology and the lenses of the eyes centuries beyond Leonardo's reach, but, in the 1470s, the artist had little ability in Latin, and so even the writings of the medieval authorities on optics, Alhazen, Pecham, and Witelo were largely inaccessible to him. (10) Consequently, when he created the Munich and Benois Madonnas, he had only rudimentary ideas about the mechanics of sight, probably learned primarily from the writings of the architect and art theorist Leon Battista Alberti. (11) Following Alberti, Leonardo, at least into the 1490s, adhered to the Platonic theory of emission in the operations of sight--the belief that the eyes emit rays that extend to the object seen. (12) (This is, of course, contrary to the true nature of sight, which involves intromission, the reception of light from all object into the eyes.) Leonardo speaks of these fanciful visual rays in one of his earliest surviving notes on optics, on a sheet at Windsor Castle (about 1483-85; no. 19148): 'I say the eye projects an infinite number of lines, and these attach themselves to or mingle with those that come towards it which emanate from the things seen.' (13) A fuller explanation of this imaginary phenomenon was provided by Alberti in his Treatise on Painting, from which it is useful to quote at length: