"if a body meets a body"

In chapters 21&22 Holden talks with his little sister Phoebe.  While talking Phoebe asks Holden if he got  kicked out of Pencey.  He tries to get out of answering the question.  Eventually Phoebe asks him what he wants to do in life.  It takes him awhile but he says that he imagines a field full of children with a steep cliff on one side.  Holden says he's there to catch any kid that's not paying attention.  He almost saying that the cliff is the fall to growing up and being fake and phony and that he's trying to stop that from happening but it doesn't always work.