One important point made in the passage is that a modern writer, before he starts to write, ----.

The primitive story-teller, free from all considerations
of form, simply told a tale. “Once upon a time”, he
began, and proceeded to narrate the story to his
listeners, describing the characters when necessary,
telling what they thought and felt as well as what they
did, and adding comments and ideas of his own. The
modern fiction writer is artistically more selfconscious.
He realizes that there are many ways of
telling a story; he decides upon a method before he
begins, and may even set up rules for himself.
Instead of telling the story himself, he may let one of
his characters tell it for him; he may tell it by means
of letters or diaries; he may confine himself to
recording the thoughts of just one of his characters.