When asked to share the last great book he read, Vladimir Restoin-Roitfeld named Annie Cohen-Solal's biography, Leo and His Circle: The Life of Leo Castelli
Born in Trieste, Italy, in 1907, Castelli was an art lover and collector that opened his first gallery at the age of fifty; his first show was held in his apartment and consisted largely of works that he owned by Robert Delaunay, Jean Dubuffet, Alberto Giacometti, Willem de Kooning, and Jackson Pollock. He had a gift for discovering and cultivating talent and his stable included a long list of artists: 
Leo Castelli by Andy Warhol (1975)Richard Artschwager, Norman Bluhm, Lee Bontecou, John Chamberlain, Christo, Hanne Darboven, Ronald Davis, Willem de Kooning, Friedel Dzubas, Dan Flavin, Edward Higgins, Jasper Johns, Donald Judd, Wassily Kandinsky, Ellsworth Kelly, Joseph Kosuth, Roy Lichtenstein, Robert Morris, Bruce Nauman, Kenneth Noland, Claes Oldenburg, Jackson Pollock, Larry Poons, Robert Rauschenberg, James Rosenquist, Ed Ruscha, David Salle, Salvatore Scarpitta, Julian Schnabel, Richard Serra, Keith Sonnier, Frank Stella, James Turrell, Cy Twombly, Andy Warhol, and Lawrence Weiner among them.
I was intrigued to learn that Castelli provided his artists with monthly stipends upon which they could depend for art supplies and living expenses, what a novel concept! This brilliant move alone likely accounts for much of his success... Note also Castelli's chic attire, another likeness to Vladimir. To learn more about the fascinating life of Castelli, read "Leo the Lion: How the Castelli gallery changed the art world" in the New Yorker or his obituary in The New York Times.
Leo Castelli posing with works by Frank Stella, Jasper Johns, Lee Bontecou, Edward Higgins, and Robert Rauschenberg (1960)Leo and His Circle: The Life of Leo Castelli image courtesy of Knopf. Leo Castelli photograph © 1960 Condé Nast.