A May exhibit at the National Gallery of Art will explore the relationship between Mary Cassatt and Edgar Degas, as new evidence suggests a bond of mutual admiration and influence, rather than teacher and student. (Jessica Rosgaard & Jhaan Elker/The Washington Post)

They were friends and colleagues, and they deeply admired each other’s art. But an important exhibition at the National Gallery of Art, opening May 11, argues that the relationship between the older French artist Edgar Degas and the younger American artist Mary Cassatt was not that of teacher and student, or master and imitator. Rather, the influences flowed both ways, with Cassatt playing an important role in introducing Degas to American collectors.

This mid-size exhibition is sure to be popular with audiences already enthusiastic about the work of Degas and Cassatt. But it also the first major exhibition in a century to exhibit the two artists side by side and invite a prolonged look at role each played in the other’s evolution. “We have been able to bring together works that in many cases haven’t been seen outside their home institutions in decades,” says Kimberly Jones, associate curator of French paintings. And the exhibition will also include some work that has been newly restored, including one of the Gallery’s masterpieces, Cassatt’s 1888 “Little Girl in a Blue Armchair.”

That stunner, in which a bored little girl seems to be sliding off what is now a brilliantly blue chair, is one of the works in which close study has revealed powerful engagement between Degas and Cassatt. Earlier this month, Jones pointed to a patch of gray in the painting’s background, where two walls seem to come together in a shadowy corner.

“This painting is really in many ways the star of the show and a bit of a smoking gun,” says Jones. After a restoration of the work and a close examination of the surface of the painted corner, curators at the gallery believe that Degas may have been the author of this detail. Jones thinks he likely picked up Cassatt’s palette, sketched in the corner, and then turned the painting back over to Cassatt, who had to accommodate this new detail to the larger scheme of the image.

“We really do believe that he essentially just gave her that hint, that little nudge in the right direction and then said, ‘okay, now you’re on your own,’” says Jones. “And she then had to make it work. And she did it in a phenomenal way.” Indeed, the corner draws the viewer’s eyes into the painting, which then takes on an almost circular motion, from foreground to background to foreground again, culminating in the little girl who almost seem in motion herself.

Mary Cassatt. “Little Girl in a Blue Armchair,” 1878, oil on canvas. (Courtesy National Gallery of Art, Washington)

Cassatt may have the most to gain in the public’s reevaluation of the two artists. She is an indoors painter, a master of domesticity and the nuances of family life. And perhaps that has led too many people to overlook the larger public role she played during her career and her daring as an artist. Yet, with the exception of a few paintings made after 1886, this exhibition doesn’t focus on the usual Cassatt subjects, mothers and children. But it will include nudes, which Jones believes will surprise many visitors.

“I think we’re accustomed to knowing that Degas was avant-garde and edgy, but people don’t think of Cassatt that way,” she says.

Degas/Cassatt will include some 70 works, in a variety of media, focusing most intently on the 1870s and ’80s, when the back-and-forth between the two artists was at its most intensive and productive.

Five others to watch

Photographer Garry Winogrand, who documented New York City in the middle of the last century, died in 1984, but there hasn’t been a major retrospective of his work in a quarter century. That will change when the National Gallery presents some 160 of his photographs in an exhibition, opening March 2, that is being co-organized with the San Francisco Museum of Modern Art. A reviewer for the San Francisco Chronicle found new insights into Winogrand’s vision, including a powerful sense that his view of the world — or perhaps the world he was viewing — darkened over the decades Winogrand documented.

●The years Winogrand witnessed also brought the popularization of what we now call “the cool,” a peculiarly American aesthetic of detachment and existential unflappability. American Cool, opening Feb. 7 at the National Portrait Gallery, delves into this now-ubiquitous ideal of personal sophistication, with photographs that document its emergence in the jazz world of the 1940s to its now thoroughly commodified form in all aspects of culture. Photographers include Henri Cartier-Bresson, Annie Leibovitz, Richard Avedon and Diane Arbus.

●The Phillips Collection also looks to America — the contributions of American artists to its own rich holdings of late 19th- and 20th-century art. Made in the USA: American Masters from The Phillips Collection, 1850–1970 features 120 artists and 200 works, making it about as ambitious an exhibition as the charmingly land-strapped museum can mount. Look for works by Milton Avery, Stuart Davis, Richard Diebenkorn, Arthur Dove, Edward Hopper, Jacob Lawrence, John Marin, Robert Motherwell, Georgia O’Keeffe, Mark Rothko, John Sloan and Clyfford Still, among others.

●“ Gravity’s Edge,” opening Feb. 7 at the Hirshhorn, is also drawn from the museum’s own collection, but with a particular determination to explore “the force of gravity as a determining factor in artistic production and the increasing attention paid to the edge as a compelling aspect of the structure and perception of an artwork.” It will reexamine work by artists such as Helen Frankenthaler, Morris Louis and Kenneth Noland, connecting vision and style to the larger evolution of abstraction after the rough-and-tumble days of the abstract expressionists of mid-century painting.

●Finally, the National Building Museum will devote an exhibition to the modernist landscape designer Dan Kiley , opening Feb. 8. Organized by the Cultural Landscape Foundation, the exhibition uses photographs to document the work of Kiley, whose designs were rigorously geometrical and contemporary. Kiley, who worked with legendary architects Eero Saarinen, Louis Kahn and I.M. Pei, contributed to more than 1,000 projects around the world during his long and productive career.