“Mandorle,” the Italian word for almonds, altered the course of Walter Benjamin’s life. It was in 1924, on the island of Capri, where the German critic and scholar had traveled to reorganize his life and rework his failed dissertation, that he helped the beautiful Latvian actress Asja Lacis purchase nuts in a local piazza. “I have been noticing you for two weeks,” he would later tell her, “how, in your white dresses, you and [your daughter] Daga who has such long legs, didn’t walk across the piazza but fluttered.”

After working up his courage, he translated for her, then carried home her groceries, dropping all of them halfway to her home. Nevertheless, a bond was struck, and a love affair began that would lead to his divorce from the writer Dora Kellner. The affair would have an unmistakable impact on his academic work. Lacis, a committed revolutionary and a working actress, would introduce him to both communism and the professional theater, two forces that would change his thought forever.

“Shadowtime,” Brian Ferneyhough’s new opera, which opens at the 2005 Lincoln Center Festival later this week, chronicles on stage Benjamin’s life and ideas. Some might find it strange that this reserved, bookish figure should be at the center of a lavish theatrical production. But Benjamin would be delighted. Though best known as a man of letters, Benjamin was a lifelong devotee of the stage, and his writings on the theater helped to change the course of 20th-century drama.

Benjamin showed interest in the connections between theater and philosophy long before his journey to Capri. In his rejected doctoral dissertation, later published as “The Origins of German Tragic Drama,” he argues for an allegorical, almost mystical, reading of the Trauerspiels, or “mourning dramas,” popular in 18th-century Germany. Concluding that “tragedy is the preliminary stage of prophecy,” Benjamin contends that the plays are expressions of a complete world philosophy in themselves. This line of thinking would develop further after his encounter with Lacis.

Through her, Benjamin met some of the greatest stage personalities of his day, including Kurt Weill and Bertolt Brecht, with whom he became close personal friends. More importantly, Lacis introduced the studious Benjamin to the working world of the theater. The actress spent most of her life in Moscow, running a company designed to teach children the value of Marxist revolution. In 1926, Benjamin traveled to the city to be with her and observed firsthand the machinery of Soviet political theater.

Benjamin, who always remained skeptical of communist orthodoxy, dismissed the content of Lacis’s plays. But he was fascinated by the use to which the communists were putting drama: Here was philosophy, or at least ideology, being communicated through action rather than words. “Every spectator is enabled to become a participant,” he observed. His interest led to long conversations with Brecht, ho himself had a stint writing the kind of propagandistic plays Lacis produced.

Along with others like the director Erwin Piscator, Brecht had turned away from “agitprop” heater to develop what he called an “epic theater,” a kind of quasi-documentary drama that carefully presented social conditions to the audience rather than emotionally involving them in a storyline. This model of story telling would prove highly influential on Benjamin’s philosophy.

Though he would come to consider himself a Marxist, Benjamin abhorred Marxism’s emphasis on dialectical thought. Influenced by Jewish mysticism, Benjamin took issue with this linear view of time and narrative. In drama, and particularly in Brecht’s epic theater, he found another model – one where multiple viewpoints competed for attention and no narrative voice decreed right and wrong.

Benjamin even penned a series of monographs on the concept of epic theater, arguing that philosophy should take its cue from drama and eschew dialectics for a more multi-faceted view of the facts. This poetic and fragmentary approach to academic work is one Benjamin himself aspired to. It is especially evident in the massive, unfinished “Arcades Project,” started shortly after his meeting with Lacis, in which he attempts to present a bird’s-eye view of 19th-century Paris. Benjamin referred to the project as “the theater of all my conflicts and all my ideas.”

Even as they influenced his own thought, Benjamin helped give intellectual weight to Brecht and Piscator’s experiments, and was a major force in popularizing their ideas. He wrote in his published correspondences that his friendship with Brecht was “one of the most important and most strategic points” in the development of his thought, and he would offer an extensive treatment of Brecht and Piscator’s work in a series of essays published throughout the 1930s, including “What is Epic Theater?”, “Conversations with Brecht,” and “The Author as Producer,” eventually collected as “Understanding Brecht” in 1955.

Later, in the late 1960s, the revived interest in Benjamin’s writings would be sparked in large part by an interest in Brecht, and some of his most prominent English-language champions, including Susan Sontag, originally came to him as a commentator on the playwright. “What is Epic Theater?” was one of the first of his pieces to be translated into English in 1968, and “Understanding Brecht” as only the second book-length work by Benjamin to become available in this country, in 1973.

Mr. Ferneyhough’s “Shadowtime,” which begins with Benjamin’s suicide at age 48 and follows him through his experiences in the afterlife, is not strictly a documentary drama or a meditation on social conditions. It is an examination of Benjamin’s life work presented in dramatic form – the form Benjamin himself would argue was best suited to his unique intellectual ambitions.

Today’s ubiquitous documentary dramas – from the Culture Project’s examination of capital punishment in “The Exonerated” to the Builders Association’s look at Third World outsourcing in “Alladeen” – finds its intellectual roots in epic theater. In Tony Kushner’s “Angels in America,” the character of Prior Walter is named in homage to Kushner’s intellectual ancestor.

That Benjamin’s connection to the theater is today largely forgotten suggests how little is really understood about this idiosyncratic thinker. If Benjamin had his way, the theater might be the place where most of us today would encounter his ideas – and philosophy in general – in action.

“Shadowtime” will be performed July 21 & 22 (Lincoln Center, 212-721-6500).