“for we all of us, grave or light, get our thoughts entangled in metaphors, and act fatally on the strength of them”
Here we get everyone’s opinion of everyone else at the dinner party. We also see the beginning of disillusionment Casaubon is having about the marriage. He seems to think he’s owed happiness. She seems to think her real happiness is to come. Lydgate knows it’s because she’s “too earnest”.