Who visits Joe and pip in chapter 18? What news does he bring concerning pips "great expectstions"? What two conditions must be met?

Jaggers visits Joe and Pip. He explains that Pip now has "great expectations." He has been given a large amount of money, to be administered by Jaggers, by an anonymous sponsor whom Pip is never to try to discover. Fulfilling Pip's dreams, Jaggers explains that Pip is to be "brought up a gentleman" and will be tutored by Matthew Pocket -- the same "Matthew" that had been mentioned at Miss Havisham's. Jaggers gives him money enough for new clothes and leaves, expecting to meet him in London within a week.