When people talk about famous art collecting families of the early 20th century, they talk about the Guggenheims, the Mellons, the Rockefellers — not about Sterling and Stephen Clark. That is one reason the director of the Sterling and Francine Clark Art Institute, Michael Conforti, decided to mount an exhibition devoted to the brothers’ collecting lives for the Art Institute’s 50th anniversary in 2005. “The Clark Brothers Collect: Impressionist and Early Modern Paintings,” which previously showed at the Art Institute in Williamstown, Mass., will open on May 22 at the Metropolitan Museum of Art, of which Stephen was a major patron.

The two brothers, who were heirs to the Singer sewing machine fortune, collected passionately. While their tastes differed, the strengths of their collections also dovetail nicely: Sterling, who preferred attractive pictures and traditional virtuosity, focused on high Impressionism, while Stephen was drawn to the Post-Impressionists and Modernists. The exhibition brings together three great Post-Impressionist paintings from Stephen’s collection: Georges Seurat’s “Circus Sideshow” and Cézanne’s “The Card Players,” both from the Met’s collection, and Van Gogh’s “The Night Café,” from the Yale University Art Gallery. “Those three haven’t been seen together since they left Stephen Clark’s 70th Street townhouse,” the curator of the Met show, Susan Stein, said.

The Clark brothers are not often thought of together in part because they were estranged: In the 1920s, Sterling sued Stephen and their other two brothers over the trusts that controlled the Singer fortune. Although the immediate cause of the dispute was financial, it had roots in longstanding personality differences.

Sterling, who was the second eldest, was an adventurer with an Old World sensibility. After graduating from Yale, he joined the army and fought in the Philippines and China. In 1910, he settled in Paris, where he married an actress from the Comédie Française and restored a mansion in the 16th Arrondissement. Through decorating his house, he began collecting art — starting with old masters, and later “moderns” like John Singer Sargent and Renoir. But “[h]e drew the line at Cézanne,” whom he believed couldn’t paint, Ms. Stein said. “He stopped at the artists who broke the rules.” When Stephen began to collect, Sterling often criticized his purchases, telling him he had spent too much, or that the works he’d gotten were not authentic.

Stephen, the youngest of the four brothers, was the rational, responsible one, who stayed in New York and managed the family’s interest in the Singer company. But, if his life was more conservative than Sterling’s, his taste was more progressive: He collected works by, in addition to Cézanne and Van Gogh, Matisse, Picasso, Thomas Eakins, and Edward Hopper.

Each disposed of his collection differently. Sterling, who saw his collection as an entity and an achievement to be preserved, wanted to found a museum. The administration of Williams College wooed him and won. Stephen divided his collections among the institutions he supported: the Met, the Yale University Art Gallery, and the Museum of Modern Art, where he was a founding trustee.

Ms. Stein has organized the Met show into rooms that draw specific contrasts between the brothers’ collecting choices. Early rooms will compare similar Impressionist still lifes that the brothers bought, and include paintings that at different points belonged to both brothers. Later rooms juxtapose pairs of paintings such as Sargent’s portrait of Carolus-Duran, from Sterling’s collection, and, from Stephen’s, Eakins’s “Dr. Agnew,” with its grittier sensibility.

The difference in the brothers’ tastes invites psychological interpretation, though Ms. Stein said she tried to avoid imparting motives where the brothers themselves left no records. But she suggested that the relationship between Sterling’s adventurousness in life and conservatism in art, and Stephen’s reserve in life and progressive taste in art, is perhaps not so paradoxical. In some ways, Sterling was living in the past of an idealized Old World, while Stephen was rooted in the present — and therefore more interested in contemporary art.

“Sterling kind of lived outside of conventional society,” Ms. Stein said. “Whereas Stephen is very much grounded in the present day. He’s running the Singer Company. He’s paying the servants. He’s a trustee of the Metropolitan and the Museum of Modern Art.”

The author of a new book on the brothers, “The Clarks of Cooperstown,” Nicolas Fox Weber, said in an interview that, to him, Stephen’s taste in art suggests hidden depths to his personality. “He was a man who lived in two splendid townhouses on East 70th Street and had a beautiful house in the country,” Mr. Weber said, yet he was drawn to Van Gogh’s visions of madness, and to the melancholy of Hopper. “He and his wife could eat at the fanciest restaurants, yet he wanted a painting of lonely people at a soda fountain,” Mr. Weber said.

Even Mr. Conforti, who presides over Sterling’s collection at the Clark Art Institute, acknowledged in an interview that the greatest paintings in this exhibition are the Post-Impressionist works collected by Stephen. But he has other reasons to be satisfied. Before this exhibition, the Clark Art Institute had no association with the descendants of the Clark family in Cooperstown, where Stephen founded three museums. But Jane Clark, Stephen’s granddaughter, supported the exhibition and even came to the Clark Art Institute and met Sterling’s step-granddaughter. The night before the opening in New York, Mr. Conforti and Ms. Clark are hosting a party together at the Explorers Club at 46 E. 70th St. — Stephen Clark’s former townhouse.

“It really has brought the Clarks together in a surprising way,” Mr. Conforti said of the exhibition. “I never would have expected that.”