His ambition to write may have prompted an exchange with T. S. Eliot, then in his late 50s, on the day they met in 1946, when Mr. Giroux, “just past 30,” as he recalled the moment in “The Oxford Book of Literary Anecdotes,” was an editor at Harcourt, Brace. “His most memorable remark of the day,” Mr. Giroux said, “occurred when I asked him if he agreed with the definition that most editors are failed writers, and he replied, ‘Perhaps, but so are most writers.’“