Dorothea brings up the subject after having been at Fres***t for a week. She wants to start thinking about who's going to take over as the new vicar at Lowick.
Historical Context Time! We should take a moment to explain why deciding who's going to be the next vicar of Lowick is such a big deal. Being a clergyman was considered a "genteel" occupation. In other words, it was pretty high on the social scale. But some parishes were bigger than others, and therefore, had higher salaries for the resident clergyman. Lowick is a big parish, and the "living," as it was called (meaning the salary for the clergyman), is pretty good. The only reason Casaubon was the clergyman in addition to being a big property owner is that he had an older brother. The oldest son always inherited the family estate, and the younger brother had to choose some relatively "genteel" profession (like becoming a clergyman) to support himself. Fortunately for Mr. Casaubon, his big brother kicked the bucket early on, so he ended up with both a huge estate and the living at Lowick. So now that he's dead, Dorothea has to decide who's going to take the sweet job as vicar of Lowick.
Back to the story…
Mr. Brooke tells her to put off making any decisions about anything, and then takes off like a shot. He doesn't want to be around when someone tells her about Casaubon's codicil.
Celia decides it's her job, as the sensible sister, to break the news.
Dorothea can't believe that Casaubon had these suspicions about Will and herself.
Lydgate arrives just then, and tells Celia and Sir James that Dorothea's over the shock now, and should be allowed the freedom to do whatever she likes.
Dorothea would have done anything for Casaubon while he was alive, because she pitied him; but now that he's dead and has shown how much he didn't trust her, she doesn't feel obligated to do a darn thing.
She looks through Casaubon's papers, but doesn't find much in the way of instructions about how he wanted her to carry on his work.
She's kind of relieved about that, and starts to think again about who should be the new vicar.
Her uncle recommends Mr. Tyke (the man Bulstrode appointed as the chaplain of the new hospital, with Lydgate's reluctant vote against Mr. Farebrother).
But Lydgate recommends Farebrother for the vicarage at Lowick, and recommends him so highly that Dorothea is immediately interested.
Lydgate doesn't leave out Farebrother's faults (the card playing), because he doesn't want Dorothea to hear about it from someone else, later.