"Abroad," said Miss Havisham; "educating for a lady; far out of reach; prettier than ever; admired by all who see her. Do you feel that you have lost her?" (15.69)
The concept of high society in this novel is often likened to heights and to the sky. But Pip's climb up the social ladder is more like a bridge to nowhere than a stairway to heaven.
And now, because my mind was not confused enough before, I complicated its confusion fifty thousand-fold, by having states and seasons when I was clear that Biddy was immeasurably better than Estella, and that the plain honest working life to which I was born, had nothing in it to be ashamed of, but offered me sufficient means of self-respect and happiness. (17.74)
Pip is divided here between the familiar and the, well, sexy. Biddy is familiar, which makes her common in a literal sense: it's common for Pip to see her, because she basically lives with him. Estella is uncommon not because she's beautiful and well-education but because he doesn't spend a lot of time in close contact with her. Learning to value the common is part of Pip's growing up.
"It is considered that you must be better educated, in accordance with your altered position, and that you will be alive to the importance and necessity of at once entering on that advantage." (18.63)
Apparently, certain kinds of education (most likely involving dead languages) are more valuable than others (like how to work a forge). Interestingly, we never get to see Pip "learning" in London, though apparently, he's at it all the time.
I hope I've helped you,
Angela