It is in Chapter 36 where Pip makes a resolution to use his financial wealth to help his friend, who is clearly not as well off as Pip is economically. He decides to try and buy him a partnership in a business, so that he is able to earn a good living. This is something that he is only eventually able to accomplish with the help of Miss Havisham in Chapter 49.
Crucially, this event signals the beginning of Pip's moral regeneration, as he realises that his wasteful habits and squandering of his wealth are in danger of corrupting Herbert, as we see in the part-comic, part-tragic Chapter 34 where they compare their debts and resolve to do something about it, only spending more money in the process.
This seems to point towards a theme of the novel - the opposition between industry and idleness. When Pip is given wealth without having to earn it, he quickly falls into debt and dissipation. It is crucial therefore to note that at the end of the novel he becomes socially a middle class businessman who works for his living. Dickens seems to be questioning the definition of a "gentleman" through the novel, suggesting that a real "gentleman" is defined by social responsibility rather than mere high manners.