According to the beginning of Chapter 21, what makes a story or narration truly effective and worthwhile?

At the start of Chapter 21, the author lays out a clear philosophy on what constitutes a powerful narration. He posits that a speaker's words are in vain if they don't evoke a deep physical and emotional response in the listener. An effective narration is one where the listener sways upon hearing it, the hair on their body stands on end, their throat chokes up with emotion, and tears of love and joy flow from their eyes. The chapter suggests that any narration which fails to delight the listeners in such a profound manner is considered futile.