Readers who relished the wit and verve of “The Letters of Noël Coward,” a delightful epistolary chronicle of the actor-playwright-composer-lyricist-director’s life on and off the stage, will seize eagerly on a new volume of Coward’s writings. “Noël Coward On (and In) Theatre” celebrates the art form that claimed Coward’s devotion from the time he was, by his own admission, “a brazen, odious little prodigy” of 10. London’s Little Theatre and a children’s musical called “The Goldfish” were “the theater where I was born and the play in which I was born,” Coward declared; 37 years after making his professional acting debut in 1910, he could still recall “the unforgettable, indescribable dressing room smell — greasepaint, face powder, new clothes and cold cream.” His passion for theater, from its grubbiest particulars to its headiest heights, is the thread that binds together a slightly miscellaneous collection. It has a somewhat more serious tone than its predecessor, though Coward’s nimble way with words ensures that even the sternest pieces have a light touch.

Newspaper essays, private diary entries, press interviews, poems and lyrics are among the materials assembled with extensive connective text by veteran biographer Barry Day, who did the same for Coward’s letters. Day takes an episodic approach. Chapters on playwrights, acting, actors, producers, directors and critics contain Coward’s assessments across the decades. They are interspersed among four separate chapters about playwriting, which take us chronologically through his career from juvenilia like “The Unattainable” in 1918 through the brilliant comedies of the 1920s and ’30s (“Hay Fever,” “Private Lives,” “Design for Living”) to the less popular works of the postwar years. It’s a bit startling to find musical works written from 1923 through 1964 in a single chapter near the end, but it makes a certain amount of thematic sense: Coward’s wildly successful 1950s nightclub stints in Paris, New York and Las Vegas reclaimed the songs from those shows as a major portion of his legacy and led to his renaissance in the 1960s as a grand old man of the theater after some years of being dismissed as a hidebound old fogey.

That reputation is understandable when you read Coward’s reproachful articles addressed to the Angry Young Men of post-World War II British drama, urging them to “Consider the public.” His complaints about the sordid tone of their plays are ironic, coming from someone who made his first big splash with a scandalous play about a drug-addicted young man whose relationship with his promiscuous mother has incestuous undertones (“The Vortex,” way back in 1924). But it wasn’t the subject matter of plays like “Look Back in Anger” that offended him; it was the lack of respect for “conventions and traditions which . . . have kept the drama alive and kicking for several hundred years.” What Coward meant by this was the traditions of craftsmanship, professionalism and unfailing attention to audience appeal that are the mainstays of the commercial theater.

Those were Coward’s values. “The prime purpose of the theater is entertainment,” he said in a 1961 radio interview, reiterating a sentiment he had uttered throughout his career. (It could have been reiterated less often in this overlong anthology; among the other pronouncements that become wearyingly familiar from repetition is the less-than-new opinion that comedy is harder to perform than tragedy.) Coward grudgingly admitted that there might be some merit to acting schools — “genuine talent can profit from or survive any given system of instruction” — but insisted that “the best training of all is acting to paying audiences.” Unsurprisingly, his relationship with drama critics was wary. “I think it is so frightfully clever of them to go night after night to the theater and know so little about it,” he deadpanned.

Coward’s knowledge of and reverence for theatrical tradition was matched by his regard for talent in whatever form it took; it’s this openness that saves him from sounding like an out-of-touch curmudgeon. He might prefer well-made plays with glamorous characters to avant-garde experimentation and gritty realism, but that did not stop him from appreciating the groundbreaking work of Harold Pinter, or even that quintessential Angry Young Man, John Osborne. After seeing and reading “The Homecoming,” he wrote to Pinter, “You cheerfully break every rule of the theatre that I was brought up to believe in, except the cardinal one of never boring for a split-second.” He judged Osborne’s “Look Back in Anger” to be “full of vitality and rich language,” and Osborne returned the compliment some years later when he wrote: “Mr. Coward is his own invention and contribution to this century. Anyone who cannot see that should keep well away from the theatre.”

Day includes many such comments by friends and colleagues, so that Coward’s inimitable voice is supported by a chorus of equally dedicated theater practitioners. Together, they offer a heartfelt love song to the theater, rooted in ancient traditions but always reinvented by new generations for new audiences.

Wendy Smith is the author of “Real Life Drama: The Group Theatre and America, 1931-1940.”

Noël Coward On (and In) Theatre

Edited by Barry Day

Knopf. 480 pp. $40