“If a film, of no matter what type, is to be worth while, it must be entirely dominated by the will of one man and one man only—the director.” François Truffaut, 1954? Andrew Sarris, 1964? No: Iris Barry, 1924, writing in the London Spectator. Barry is one of the secret heroines of the history of cinema—in fact, of the very idea that there is such a thing as a history of cinema. The film historian and curator Robert Sitton has written a terrific new biography of her, “Lady in the Dark” (Columbia University Press). At 7 P.M. tonight, he’ll discuss Barry and introduce a movie program dedicated to her at the Museum of Modern Art, where Barry founded the film department in the early nineteen-thirties.

In his book, which he has been working on for decades (among the interviewees is Roberto Rossellini, who died in 1977), Sitton brings to light an extraordinary story—or, rather, an extraordinary person, who has been languishing unjustly in the shadows (though Jean-Luc Godard did pay tribute to her, by name, in his film “In Praise of Love”). Barry was born in 1895 near Birmingham, England. Returning home from a convent school at seventeen, she began to frequent the movies; she had an instant passion for Charlie Chaplin’s films, which started turning up around 1916, and which helped to determine her life’s work.

Barry moved to London, became friends with Ezra Pound, published poems, had an affair (and two children) with the writer and painter Wyndham Lewis, helped with the release of “Ulysses,” married the American poet Alan Porter—and, in 1924, became the Spectator’s first film critic. Indeed, Ivor Montagu called her the “first film critic on a serious British journal.” (Soon thereafter, she also started writing for the more popular Daily Mail.) Sitton points out the political side to her appointment—the effort to promote the British film industry—and the trouble that this underlying purpose caused Barry, who particularly loved Hollywood movies. (Her remark, quoted above, about the role of the director was inspired by Ernst Lubitsch’s first Hollywood film, “The Marriage Circle,” and by Chaplin.)

As much a theoretician as a critic, Barry distinguished the art of the cinema from mere filmed theatre, emphasized the difference between movie acting and stage performance, and insisted that movies—despite their novelty and popularity—had as much artistic value and validity as plays:

ideally, the visual beauty of a film should be the aesthetic alternative to the stage’s poetry. I can conceive of films throughout which pictures of ineffable loveliness should continually melt into each other. There will be such films yet.

Like all great critics, Barry was writing about the future of the art. She also wrote a book, “Let’s Go to the Pictures,” in 1926, in which she expounded her fascinating philosophical ideas about the history, aesthetics, and potential of film. Barry considered movies, by the very fact of their photographic record, to be intrinsically documentary, but considered their informative and factual side to be inseparable from their aesthetic power: “The cinema helps us to live complete lives, in imagination if not in fact. And I cannot help thinking that knowing is the same thing as sympathizing.” She foreshadowed the distinctive modernism of the French New Wave in exalting a cinema of images—“The most beautiful plays are good to listen to: the most beautiful films are good to look at”—that is nonetheless sustained and propelled by “story value.” (Among her paragons of movie art, besides Chaplin, were D. W. Griffith, Erich von Stroheim, and F. W. Murnau.)

Barry was enthusiastic about early experiments with sound, and she recognized the historic power of talking pictures. As she wrote in 1929: “It is impossible not to speculate already on the possibility of English becoming a world-language through the screen.” But she lost her reviewing jobs—Sitton thinks that her enthusiasm for Hollywood at the expense of British movies had something to do with it—and in 1930 she and her husband moved to New York.

Poor and underemployed, she turned to a new friend here, the architect Philip Johnson, through whom she met Alfred Barr, the founding director of the Museum of Modern Art. Barr believed that the museum should have a place for movies, and he hired Barry to build what was, at first, simply the Film Library—a collection of movies. Her first program premièred in late 1934, with films by Chaplin, Walt Disney, Griffith, and Fritz Lang, as well as “Tabu,” co-directed by Murnau and Robert Flaherty. Sitton writes, “The programs, presented between October 28 and December 30, 1934, were a huge success and led to requests for showings from universities and museums throughout the country. It marked the beginning of the film art movement in the United States.”

Barry initially imagined that the library would be used to spark the creation of film-history courses in universities, modelled on art-history programs. When she went to Hollywood, in 1935, to seek donations of film prints from producers, filmmakers, and stars, she set forth her detailed outline of a cinema-studies curriculum that would include their work. (In 1938, she also co-founded, with Henri Langlois, Frank Hensel, and Olwen Vaughan—a Frenchman, a German, and a Briton—the International Federation of Film Archives). Soon, however, MOMA became more than a repository of films, more than a lending library of prints—it became, in 1939, a movie museum where those films were shown, and Barry was its programmer.

There’s a lot more to Barry’s story (read the book): her troubles with Griffith; the Red-baiting that MOMA’s employment of Jay Leyda, a Soviet film expert, and Luis Buñuel earned her; Nelson Rockefeller’s role in conscripting her and her department for the propaganda battles of the Second World War (Orson Welles’s unfinished film “It’s All True” turns up here as a sidebar); the department’s difficulties in the immediate postwar period; Barry’s personal struggles, including a bout with cancer in 1949; her separation from the museum and twenty-year decrescendo; her death, in 1969.

But MOMA, thanks to Barry, proved to be a crucial influence in the history of cinema—in the very idea of the history of cinema—and in the story of filmmaking itself. In the nineteen-forties and fifties, Langlois’s Cinémathèque Française was the key place where the future filmmakers of the French New Wave learned about movies by watching movies—where the romance of cinematic neoclassicism was born. That role was played here mainly by MOMA, where, in the early nineteen-sixties, retrospectives of the films of Orson Welles, Howard Hawks, and Alfred Hitchcock—programmed by Peter Bogdanovich, who was in his early twenties—inspired a new generation of critics and filmmakers.

It’s apt that tonight’s tribute to Barry coincides with the New York Film Festival. Barry was the guest of honor at the first N.Y.F.F., in 1963—which also held screenings at MOMA. She is, so to speak, the primordial author of the notion of the auteur. Robert Sitton has done a great thing by bringing her out from behind the screen. What’s needed next is a collection of her critical writings.