Final answer:
In chapter seven of 'Great Expectations', Pip discovers Joe's illiteracy, which is a pivotal moment that influences Pip's perception of education and social ambition throughout the novel.
Step-by-step explanation:
In chapter seven of Great Expectations, Pip learns that Joe is unable to read or write. The revelation of Joe's illiteracy deeply affects Pip since Joe is his brother-in-law, role model, and a father figure to him. Furthermore, this realization prompts Pip to reflect on his own educational opportunities and ignites a sense of social ambition, which becomes a central theme in Charles Dickens's novel.