Hannah introduces the hermit as "a perfect symbol" (1.2) for all that's wrong with Romanticism: "A century of intellectual rigour turned in on itself. A mind in chaos suspected of genius. In a setting of cheap thrills and false emotion" (1.2). The reactions the hermit provokes in other people and in society at large are more important than the hermit is as an individual.
Once Hannah starts to suspect that the hermit and Septimus are the same person, her understanding of the hermit's symbolism shifts.
HANNAH: Don't you see? I thought my hermit was a perfect symbol. An idiot in the landscape. But this is better. The Age of Enlightenment banished into the Romantic wilderness! The genius of Sidley Park living on in a hermit's hut! (2.5)
Hannah does a flip-flop here. Now that she thinks the hermit was actually on to something with his scribbling, he's become the misunderstood genius (an oddly Romantic notion) unappreciated by a stupid public. It's interesting that, even though Hannah's completely altered her reading of the hermit as symbol, the point she's trying to make through that symbol remains the same: Enlightenment rules, Romanticism drools. Does Hannah's ability to use two different symbols to prove the same thing indicate that her idea is true?