what is Froster's overall point about joueneys or trips in literature?

I think Froster is saying that the student must be able to identify certain archetypes of literature in a given story. So, when he uses the story of Kip buying the bread and seeing his dream girl swept up by the popular rich boy, Kip decides to join the Marines. Really what we are looking at is the hero's quest, little different from say King Arthur. Journey's and trips in literature take place in many different situations yet follow a particular shared context.