What is the meaning behind Pip placing Joe's child (also Pip) on his parents' tombstone?

In the beginning of the novel, Pip is in the graveyard, visiting his dead parents and siblings. When Magwitch meets him, he puts Pip on top of the gravestone. His life following this “placement” leads eventually to his “great expectations.” Though there was great turmoil and suffering along the way, Pip reaches a place where his destiny is one of security and contentedness, though it is not the type that he had expected it to be. By placing his namesake on the gravestone, Pip is symbolically starting young Pip Gargery on his own path to great expectations. The story has come full-circle, and Pip the elder has placed himself in that role of a mentor, to lead the child along his road of destiny, something which Pip himself had not had.