What qualities define a powerful spiritual narration, as described at the beginning of Chapter 21?

The introduction to Chapter 21 sets a standard for effective spiritual storytelling, emphasizing the listener's emotional and physical response. The author suggests that a speaker's words are in vain if the listener does not "sway upon hearing them" or if the "hair on the body does not stand on end." The narration is considered futile if listeners are not delighted, their throats do not "choke up with emotion," and "tears of love and joy do not flow from the eyes." This passage from Chapter 21 highlights that the true measure of a spiritual story is its ability to evoke a deep, tangible, and devotional experience in the audience.