Louisa’s dog Caesar symbolizes Louisa’s belief that a hermetic life is a peaceful one. When he was a puppy, Caesar—then Louisa’s brother’s dog—bit a neighbor’s hand (and the neighbor still has the scars). Given the choice of either putting the dog down or keeping him permanently away from the people of the town, the brother chained Caesar in the backyard and built him a little hut to live in. For the last fourteen years, this is where Caesar has lived, and Louisa feeds him a diet of corn mush so that his temper never flares at the taste of meat. Louisa is terribly fearful that, if she is to marry Joe, Joe will release Caesar from his small, confined home and he might be free to roam the town—and maybe hurt someone again. Louisa is certain that Caesar must stay in his “little hermit hut,” or chaos will follow, and this matches her confidence that she is better off alone in her own home, rather than married to Joe. The story, then, suggests that Louisa’s life as a “nun” and Caesar’s life as a “hermit” assure each of them the most peaceful existence.
Of course, the symbol of Caesar in “A New England Nun” leaves potential for other interpretations. Unlike Louisa, Caesar is confined without having a say in the matter, and the story does list all of the things that the dog has forgone because of his detention. Caesar’s punishment for a crime he committed at a very young age could read as unnecessary corrective punishment by Louisa, which would significantly change the meaning of the symbol.