By the next day, Dorothea's already decided that Mr. Casaubon's the man for her, moles and all.
She feels that she'll be able to learn from him. Dorothea has a sense that there's a whole world of knowledge out there that she hasn't been able to access, and she thinks that Mr. Casaubon will give her the key to the world's knowledge.
She's pretty sure that he's considering the idea of proposing to her, and she's grateful to him for even thinking of it – she feels so unworthy next to his great knowledge and vast wisdom.
Dorothea's wandering around, thinking of how great Mr. Casaubon is, when Sir James Chettam shows up on horseback.
Dorothea still thinks he's interested in Celia (when he's actually obviously hitting on her), and is irritable with him for interrupting her thoughts.
When he asks to see her plan for improving the cottages of the tenants in the village, she warms up to him.
Celia knows that Sir James is interested in Dorothea, and feels sorry for him – she knows Dorothea will reject him.
Several days later, Mr. Casaubon comes for another visit.
Dorothea finds new reasons to like him: she loves that he doesn't engage in small talk or idle chitchat like everyone else. He only talks about important subjects, or else keeps his mouth shut.
Unfortunately, he doesn't seem to care about building better cottages for the villagers (this is, after all, Dorothea's pet project). He's more interested in the houses the ancient Egyptians lived in.
Sir James visits more often than Mr. Casaubon, and he's so interested in Dorothea's cottage plans that she begins almost to like him – of course, she only likes him as a future brother-in-law. She still doesn't realize that he's there to court her, and not Celia.