Between Light and Shadow — Leonardo da Vinci, the Man on the Border

In the largest room of the Louvre, the Salle des États, that painting sits at the center. Inside a glass case, alone. According to the Louvre, this painting has hung in this room since 1966, and since 2005 it has been placed inside a protective glass case at the center of the room. The reason is simple: the poplar wood panel on which it was painted has warped over time and developed cracks, so it must be kept inside a climate-controlled glass case. The most famous face in the world sits there, enduring the warping of a single sheet of wood.

The woman in the painting is believed to be Lisa Gherardini, wife of the Florentine silk merchant Francesco del Giocondo. The Louvre states that she is painted against a distant landscape. Her half-turned pose, her clasped hands, and that smile. The Louvre calls it simply that famous, enigmatic smile. The description goes no further than that. No one states with certainty what the smile means. Perhaps that is exactly how this painting has lived so long.

What the Louvre and Smarthistory both point to is technique: sfumato. This Italian word, meaning "like smoke," refers to a method of layering thin glazes of paint to blur outlines and soften the transition from light to dark. Leonardo himself is said to have described it as being without line or border, like smoke. The oil paint newly introduced to Italy made this possible. Unlike quick-drying tempera, oil paint could be layered again and again in transparent coats.

That is why there are no lines on her face. Around her eyes and mouth, instead of a sharp boundary, there is a blurred region where light and shadow bleed into one another. The more we try to grasp that smile, the more it slips away — perhaps because there was never an outline there to grasp in the first place. Leonardo did not paint a face. He painted the light passing over a face.

The Convent of Santa Maria delle Grazie in Milan. In the room where the monks once ate together, on that wall, is The Last Supper. It was commissioned by Ludovico Sforza, Duke of Milan. At the very moment Jesus says that one of his twelve disciples will betray him, Leonardo captured the ripple of unease spreading down the table, all within a single wall.

The trouble is that he did not follow the traditional method of painting a mural. According to Smarthistory, rather than fresco — painting quickly onto wet plaster, as Giotto had done in the Arena Chapel — Leonardo chose to mix oil and tempera and paint onto a dry wall (a secco). The dry wall could not absorb the paint. As a result, within just a few years of its completion, the painting began peeling from the wall.

Why did he do it? Perhaps the pace of fresco simply did not suit him. Wet plaster must be painted quickly before it dries, and once painted, it is difficult to correct. But Leonardo was a man who revised. He layered glazes for sfumato, stepped back and approached again, and looked for a long time. The moment he tried to bring that slow method to the wall, the painting's very lifespan was put at stake.

The painting endured centuries of damage and overpainting. Following a massive 20-year restoration completed in 1999, it is said that less than half of the surface we see today is Leonardo's original work. Restorers filled the irrecoverable portions with beige watercolor. Even now the painting is fragile, and visitors are admitted in small groups, allowed to stand before it for only 15 minutes. Fifteen minutes — a fixed span of time to protect something that is vanishing. And yet, even before that half-remaining wall, people still read the tremor of that moment. Some paintings are remembered longer not because they remain whole, but because they are in the process of disappearing.

There are two versions of the same painting. One hangs in the Louvre in Paris, the other in the National Gallery in London. The composition is nearly identical: a cave draped in rock, lush vegetation, and four figures gathered within — the Virgin Mary, the infant John the Baptist, the infant Jesus, and an angel. The National Gallery's description notes that they communicate with one another in silence, with the angel serving as a heavenly witness to the scene.

Why two paintings? In 1483, the Confraternity of the Immaculate Conception in Milan commissioned this work as the central panel of an altarpiece, but a dispute reportedly arose over payment. Most art historians consider the Louvre version (c. 1483-1486) to have been painted first, and the London version (c. 1491/2-99, and 1506-08) to be later. The explanation given is that during the ongoing dispute, Leonardo sold the first painting to someone else for a higher price, and painted a second one for the confraternity.

The differences between the two paintings are quiet but distinct. According to the National Gallery, in the London version, the angel no longer points a finger at the infant John the Baptist, nor does it look out at the viewer beyond the painting. In the Louvre version, by contrast, the angel points at John and casts its gaze directly at us. A single gesture, a single glance — that alone changes the air of the two caves. Even the flowers differ: the plants in the Louvre version are said to be botanically accurate, while those in the London version are imagined.

The National Gallery explains that Leonardo blurred the edges of the figures, giving the impression that they emerge from the darkness. Here too, he erases the line. Where the cave's darkness meets the figures' bodies, there is shadow rather than boundary. Following a recent cleaning, National Gallery curator Luke Syson stated that, based on the quality revealed, the London version was mostly painted by Leonardo's own hand, and that the involvement of workshop assistants was far smaller than previously thought. The two caves now hang on the walls of different cities, each keeping the same silence in its own way.