Leonardo's Optics In Action, In Paint - WSJ.com

Inventor, mechanical engineer, architect, hydrologist, anatomist of the body and brain—Leonardo da Vinci (1452-1519) could do all these things. But how did he make his daily bread? Fascination with his proto-scientific explorations have made his main professional endeavor of painting seem like a hobby.

Mus?e du Louvre/RMN / Franck Raux

Leonardo made two versions of 'The Virgin of the Rocks,' one in 1483 (pictured) and the second roughly a decade later.

The exhibition now on view at the National Gallery, "Leonardo da Vinci: Painter at the Court of Milan," curated by Luke Syson, returns the focus to Leonardo's painting. Consisting of more than 60 paintings and drawings by Leonardo, the exhibition brings together the largest number of his surviving paintings, including previously unseen loans. It frames his work in relation to the patronage of Ludovico Maria Sforza (1452-1508), and in so doing extracts him from the floating world of the itinerant "genius" and places him in the professional milieu of the court.

The centerpiece of the show is its comparison between two major, large paintings, "The Virgin of the Rocks" from Paris and London, never before seen together.

A dispute over the first commission of 1483, for the Confraternity of the Immaculate Conception, forced Leonardo to paint a second version of the same subject—no doubt a nightmare for him, but an art historian's dream. Identical in composition, but made roughly a decade apart, the two works provide an ideal laboratory for exploring how his approach to painting developed over this important decade in his career.

Leonardo da Vinci: Painter at the Court ff Milan

The National Gallery, London

Through Feb. 5

The Paris painting, the earlier of the two, shows Leonardo still very much beholden to his master Verrocchio. The features of the Virgin and angel are extremely delicate, an impression only increased by the actual fragility of the painting. The London painting, fresh from cleaning, is a startling combination of naturalistic modeling of figures and otherworldly landscape. Leonardo used a limited palette and subtle variations of shadow to create a unified effect, but the blue of the sky, water and the Virgin's robe still pop. Some of his innovations as a painter came through his fascination with the science of optics, and specifically how shadows and color interacted and were perceived.

Applying his taste for experimentation to painting had results both revelatory and disastrous. In particular, he developed a theory and practice revolving around the representation of shadows, called sfumato. The success of this method is most evident in the modeling of the faces of Leonardo's paintings, and in the way they move between light and shade. While Leonardo's writings on optics can be difficult to parse, the results are obvious in his art.

Curiously, the curators chose not to put the two paintings next to each other, discouraging direct comparison. My guess is that neither museum was enthusiastic about the confrontation, which would bring into relief different approaches to restoration and conservation. But it seems ironic, at best, that an exhibition about a painter fascinated by experimentation and science lost the opportunity to present this challenging issue to a broad audience.

The National Gallery, London

The second version of 'The Virgin of the Rocks.'

The show also highlights Leonardo's portraits. As a painter of women, Leonardo went further than Botticelli or other contemporaries in representing beauty, intelligence and psychological complexity. Of course the public already knows this through the Mona Lisa, but like so many works that have achieved the status of icons, the painting has become almost impossible to actually see (this is also true in literal terms, with the canvas encased in bullet-proof glass and surrounded by throngs of tourists). So it is good to be reminded that there were other women, with equally engaging expressions.

It is an extraordinary achievement of the show, and source of visual delight, to have two such portraits in the same room: the famous "Lady With an Ermine" (1489-90) from Kracow, Poland, understood from its origin to be a portrait of Sforza's mistress Cecilia Gallerani; and the "Portrait of a Woman," often called "The Belle Ferronière" (1493-94) from Paris. The gaze of the woman depicted in the Paris painting—who might be another of the duke's mistresses, Lucrezia—looks disconcertingly both at and through the viewer. Both women have slightly upturned lips, which are enough to suggest ambivalent emotion.

Any scholar or curator confronting a figure with such an outsize reputation as Leonardo has to think strategically about which notions to dismantle and which to leave intact. Mr. Syson made a frontal attack on Leonardo the inventor by demonstrating that the man had a day job. But he might have gone further in confronting the idea of the lone genius by showing the extent to which Leonardo thrived in Milan because of the other talents gathered there: people like Luca Pacioli, from whom he learned about geometry and mathematics; or Francesco di Giorgio, whose mechanical designs he cribbed. The show's paintings not by Leonardo are by his students, Giovanni Antonio Boltraffio and Marco D'Oggiono, rather than by his contemporaries or rivals. It must be said that Leonardo (unlike Michelangelo, but like Raphael) produced excellent students, confounding scholars eager to trace every sign of the master's hand.

In some ways Leonardo remains a difficult figure to understand. There is the problem of his genius: a label that seems to alleviate the need to explain his achievements while in fact explaining nothing. But then there are his drawings, and in them are whole worlds of imagination and research. We tend to think of genius as a sleight of hand, but the drawings on view go far in dispelling that notion. Each of the paintings on view represents the end point of numerous, rigorous studies. A sheet of studies such as those for the "Adoration of the Christ Child" demonstrates the way in which Leonardo arrived at the final composition by working through multiple, small variations on an idea.

The problem the drawings pose for the curator of an exhibition is that almost everything on the page is a tangential thought. In this case, the motive for inclusion might be a preparatory sketch for a painting in the show, but the same sheet also may include anatomy, mechanics or architecture. Together they show that while Leonardo may not have finished all the projects he started, he worked at everything he did.

Ms. Brothers is an associate professor at the University of Virginia and the author of "Michelangelo, Drawing, and the Invention of Architecture" (Yale).