The N.F.L. playoff game was still going on, mind you, while the Philadelphia Eagles star receiver A.J. Brown was engaged in some behavior you seldom see on a football sideline.

He was reading. A book. An ordinary book, not a playbook.

After the game on Sunday, which the Eagles won over the Green Bay Packers, 22-10, Brown expounded on his reading matter, the self-help book “Inner Excellence,” by Jim Murphy. He summed up the book’s message as: “Have a clear mind, and remember that nothing else matters, negative or positive.”

The book that riveted A.J. Brown.

The glimpse of a superstar athlete absorbed in reading as a game proceeded got plenty of people interested in the book and its contents, so much so that “Inner Excellence” was listed as the No. 1 best-selling book on Amazon on Monday morning, in all genres, just ahead of the dragon novel “Onyx Storm.”

Murphy, a 57-year-old from Washington State, was well aware of the sudden interest in his self-published book from 2020. “It’s such a perfect time for this to come out,” he said in an interview on Monday, “because there’s so much fear and anxiety in the world today.”

The gist of the book, he said, is that “self-centeredness is the biggest challenge we face,” adding that it leads to fear.

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