Foster says in this chapter that he wants the readers not to dismiss what the primary text is saying, although you should still pay attention to the under text and the second meaning to a message in reading. Try to recognize hidden symbols in the readings while also recognizing the original meaning. It might not be present at first, but with persistence and practice you can recognize hidden symbols in text. Foster mentions that even not as practiced readers can discover hidden symbols in movies, TV, music, and more.
An example Foster mentions is Moby-Dick, how even the many hidden symbols won't be able to save a story, it has the primary meaning of the story but also secondary implications that may be hard to recognize.