When Pip arrives in London with his "great expectations" of becoming a gentleman he experiences one of the many coincidences in the novel: He again encounters the pale young gentleman whom he fought at Satis House so many years ago. However, this time there meeting is most amicable. For Pip finds Herbert Pocket most unassuming and cordial. In fact, Herbert coaches Pip in good table manners. And, as they eat, Herbert relates to Pip the history of Miss Havisham, whom Pip assumes is his benefactress.
Herbert tells Pip two things that lead Pip to believe that Miss Havisham has a vested interest in him. One of these is the fact that Herbert reveals that he had been called to Miss Havisham's as a boy in order to meet Estella on a "trial visit."
"...and if I had come out of it successfully, I suppose I should have been provided for; perhaps I should have been what-you-may-called-it to Estella. [engaged]"
Now, Pip believes that he is in the position to become engaged, so he may, then, be "provided for" as Herbert says. Also, after Herbert relates the history of Miss Havisham, he promises Pip that he will not mention anything about Pip's having been told not to ask or discuss to whom he owes his good fortune,
"...you may be very sure that it will never be even approached by me."
When Herbert makes this remark, Pip reflects,
He said this with so much delicacy that I felt he as perfectly understood Miss Havisham to be my benefactress as I understood the fact myself.
In this passage from Chapter XXII of Great Expectations, the theme of Appearances vs. Reality is reiterated as Pip gives credence again to the apparent truth of things.