After returning from his honeymoon, Lydgate goes to Lowick to check on Casaubon. Casaubon’s hard work has always tended to produce paranoia about what others think of him and feelings of sadness about his scholarship, but it also produces a refusal to admit that he has failed. He is tormented by Ladislaw’s presence in Middlemarch and by Dorothea’s lively, insistent personality. He suspects that Dorothea is judgmental of him, which is especially upsetting considering how she once “worshipped” him as a genius. Casaubon’s suspicion and jealousy regarding Dorothea and Ladislaw intensify every day.
The bad state of Casaubon’s health makes everything worse still, as he is not sure whether he will live long enough to complete the work that he has spent thirty years preparing. He is tortured by the idea that his death would bring joy to Ladislaw, and is convinced that Ladislaw will try to marry Dorothea once she is widowed. He believes that such a union would be “fatal” to Dorothea and that he therefore has a duty to stop it.
It is unclear whether Casaubon has any genuine worries for Dorothea’s wellbeing or whether his belief that marrying Ladislaw would be a disaster for her simply results from jealousy. He can likely see that Ladislaw and Dorothea are well-suited to each other, but this makes him even more opposed to their being together.
Lydgate finds Casaubon taking a walk. Casaubon sees that Lydgate looks thin and sad. Casaubon tells him that he wants to know if Lydgate thinks his illness is terminal. Lydgate replies that he can’t say for sure, as heart disease is unpredictable, but adds that people often die suddenly and unexpectedly from it. It is possible Casaubon could live for another 15 years. Lydgate goes, and Casaubon is left confronting the inescapable reality of his own death. Dorothea goes to join her husband outside, but Casaubon reacts coldly, so she leaves him alone. She angrily wonders what she has done to deserve this treatment.
Despite knowing that he might not have much time left on earth, Casaubon can’t find it within himself to change his ways and let Dorothea in. He keeps pushing her away, which only adds to the misery they are both experiencing. Unfortunately, Casaubon is still too stuck in his ways for there to be much hope of his changing before he dies.
For the first time, Dorothea blames Casaubon, rather than herself, for the problems in their marriage. By nightfall, she decides to tell her husband that she is not feeling well and that she won’t come down to dinner. However, at this moment Tantripp tells her that Casaubon will eat in the library and doesn’t want to be disturbed. She waits until the late hour when she knows Casaubon will be asleep, then goes outside to the hallway. She sees Casaubon there, and he asks sympathetically if she was waiting for him. He takes her hand and they walk together.
The surprisingly tender moment that emerges at the end of this chapter is moving. Casaubon is presented in a decidedly unflattering way in most of the novel, but in this brief moment we see a touching, vulnerable side to him. He probably truly loves Dorothea, but has spent too many years being insecure, bitter, and lonely to properly know how to show it.