Despite Picasso's longstanding fame, one of his greatest paintings and a core work in his lifelong series devoted to the artist's studio is almost unknown. Even among Picasso scholars, few have seen the "Painter and Model" he made in 1927 or even a color reproduction of it. I have devoted 30 years to studying Pablo Picasso's art, yet I never expected to encounter its actual 46 square feet of canvas. Now, I am one of the lucky ones who has and can celebrate both the picture and the rare but growing opportunities to view it in public exhibitions.
If we drew an arc across the great years of Picasso's career during the first half of the 20th century, there would be two paramount achievements: "Les Demoiselles d'Avignon" in 1907 and "Guernica" in 1937. The first was Picasso's breakthrough as he shattered the artistic conventions of the 19th century; the second became the most powerful work capturing the humanitarian crises and political violence of the 20th century. Within the 30-year period separating these two masterpieces lies another: "Painter and Model." In my view, "Painter and Model" is not only Picasso's most important painting since "Les Demoiselles" but also the essential precedent for "Guernica." It is the missing link in the career of the greatest artist of the 20th century.
We know Picasso began "Painter and Model" with high ambitions because he selected one of the largest canvases he had used since "Les Demoiselles," and he chose the exceptional proportions of that earlier painting—a nearly square format that concentrates the composition and isolates it from the surrounding panorama of everyday things. But the strategy he employed to capture the imagination of the viewer of "Painter and Model" is radically different from the aggressive confrontation between prostitutes and audience in "Les Demoiselles."
"Painter and Model" delivers not the explicit shock of naked bodies, but the opposite—blindness, disorientation and hallucination. This monumental canvas is filled with darkness. Deep gray shadows cover much of the surface and make it so difficult to discover what lies within the space of the painting that specialists have puzzled over mediocre reproductions for years. Even in person, the composition is at first a confusing pattern of darkness punctuated by patches of light, both dazzlingly white and mellow.
As we adjust to these jolting contrasts, the situation begins to resolve into a reality both familiar and disturbing. Along the lower edge of the painting, floorboards emerge, marking the space of an interior. Near the center of this room stands a woman who might have stepped from "Les Demoiselles." Flattened to a grotesque outline of distended eyes, nose, breasts and limbs, this life-size figure is an even more hideous distortion of the human body than any in the Demoiselles, yet she is severed from that painting's sexual confrontation of prostitutes and client. She seems to stand alone in the murky, light-struck room, an emblem of the darkest experience.
Only long and careful examination reveals that she is not alone or necessarily the main character of the composition. Unlike the stark spotlight falling on the woman, a gentle, yellowish glow illuminates a crescent of space on the right side of the painting. In it resides the artist. Equally distorted, he consists only of thick rectilinear lines (unlike the curvilinear ones defining the woman) so spare and scattered that we might easily miss the figure they describe. As the golden light reveals, the artist holds his palette (a flattened "U" rotated 90 degrees and enclosing a large circle) at the end of a zig-zag arm. Crossed by both light and dark near the top right corner of the canvas, the artist's head is his most important and strangest feature. It is like a weapon—flattened into a saw-toothed, pointed blade on which two eyes are vertically aligned. An arm extends from this gaping mouth to paint with a brush on a blank canvas next to the head of the woman, his model.
Of Picasso's hundreds of images of the artist at work, this is the most horrific. Instead of it being a passive site in which the artist works quietly before a posing model, Picasso conceived the studio as a place of intellectual conflict in which artist and model engage in a creative exchange, albeit orchestrated by the artist.
"Painter and Model" shows the culmination of this struggle, one that has unlocked the most disturbing depths of the human imagination, all set in the blandest of everyday places. Picasso described "Les Demoiselles" as "an exorcism" of evil forces from the artist or viewer. In "Painter and Model," artist and audience are not separate from the danger. They penetrate the painting's hallucinatory darkness and share in the violence that transforms the model.
This willingness not only to acknowledge inhumanity but to plumb its depths was one of Picasso's greatest but least-praised achievements, far less admired than its complement—his celebration of sensual pleasure. When he reached back to "Les Demoiselles" to create "Painter and Model," Picasso gathered the tools he would need for "Guernica," whose shadowy space and writhing women bring to the public stage the private horror of the figures in "Painter and Model."
Except for the chances of the marketplace, this painting would be in the Museum of Modern Art with "Les Demoiselles." William Rubin, who led the museum's painting department from the early 1970s through the early '90s, told me that of all the Picasso paintings he sought for the museum, "this was the one that got away." When Mr. Rubin tried to acquire it from the Swiss dealer Ernst Beyeler in the '70s, another client with deeper pockets and an ambition to establish a great collection of modern Western art bought it first—the shah of Iran.
"Painter and Model" entered the state collection two years before the opening of the Tehran Museum of Contemporary Art in 1977 and four years before the overthrow of the shah. By all accounts, it has since been well protected in the basement of the museum. In 2003-04, "Painter and Model" appeared in an exhibition in Rome. In late 2010 through early 2011, it was shown at the Kunsthaus in Zurich, where I finally saw it. This last appearance has sparked discussions that may result in an exhibition that will provide the opportunity for many people to see not only this seminal Picasso but also other works in the Tehran museum's remarkable collection of modern Western art, including major paintings by Johns, Monet, van Gogh and Warhol.
—Mr. FitzGerald teaches the history of modern art at Trinity College.