Life in 19th-century Britain was governed by social class, and people typically stayed in the class into which they were born. Both as an orphan at Gateshead and as a governess at Thornfield, Jane holds a position that is between classes, and interacts with people of every level, from working-class servants to aristocrats. Jane's social mobility lets Brontë create a vast social landscape in her novel in which she examines the sources and consequences of class boundaries. For instance, class differences cause many problems in the love between Jane and Rochester. Jane must break through class prejudices about her standing, and make people recognize and respect her personal qualities. Brontë tries to illustrate how personal virtues are better indicators of character than class.
Yet the novel doesn't entirely endorse breaking every social rule. Jane refuses, for instance, to become Rochester's mistress despite the fact that he was tricked into a loveless marriage. Jane recognizes that how she sees herself arises at least partly out of how society sees her, and is unwilling to make herself a powerless outcast for love.