How powerful is a Jon Stewart book plug? Ask his wife.

Oh, to be a writer married to Jon Stewart.

Writers unattached to Jon Stewart dream of appearing on “The Daily Show.” A short segment can turn anonymity into immortality and bottom-of-the-list Amazon sales into a bolt to the top.

Before departing this week, Stewart gave one final plug to a book close to his heart.  At the close of his show on Tuesday, he turned to the camera and said: “One of the great pleasures of this show is having a pulpit to introduce an audience to books I care about – books I love. I’m going to miss that. And so before I go, I’m going to do it one more time. I have found this book by this incredible young author. Her name is my wife.”

As he does with all authors, Stewart displayed the book to the audience. A close-up showed Tracey Stewart’s “Do Unto Animals: A Friendly Guide to How Animals Live and How We Can Make Their Lives Better.” On the book’s Amazon page, Tracey Stewart is described as an animal advocate and former veterinary technician. In her husband’s words, the book, illustrated by Lisel Ashlock, “is about my wife’s journey in finding her passion to work with animals, about how you can improve your relationship with the animals in your house and in your yard.”

Though the book won’t be released until Oct. 6, Stewart encouraged his viewers to race out and order it online or from a local bookstore. “It’s incredible,” he said. “I’m so proud of her. Listen, I’ve always known my wife is a kinder and nicer person than I am. But to know that she is funnier and a better writer — I’m not going to lie to you — stings a little bit.”

After a minute and a half, the plug was over, and the promotional impact was staggering. When Stewart began his pitch, “Do Unto Animals” was ranked at 244,740 on Amazon.  Twenty-four hours later, it was at No. 11. And it kept rising. By Thursday morning, it was up to No. 7, a few notches below Dr. Seuss’s newly discovered “What Pet Should I Get?” and Harper Lee’s newly discovered “Go Set a Watchman,” and just ahead of Ta-Nehisi Coates’s “Between the World and Me.”

Stewart explained very clearly the difference between having a wildly popular television show and not having a television show at all: Pointing out why he was displaying the book on his late-night slot, he said: “When it comes out, I’m not going to have a show, and holding it up at home from what I understand doesn’t do sh–”