When Don arrives home, Betty tells him she went out for an hour to pick up some nylons, presumably for the garden party, and came back to find, as she shows Don, an entire pot full of peeled potatoes. "Carla said [Gene] thought he was on KP duty." I bet Carla would be a lot happier with him if he'd cleaned the latrines for her instead. Don takes this as a reason to suggest not attending, his ulterior motive being that he is not thrilled about hanging with Roger and Jane, but Betty says she wants to go, and she even bought a dress for the occasion. By the way, Don's pouring himself a drink here, and while it's a nice touch that he's not keeping the liquor on a high shelf, after last week I would have thought he'd go one step further and put the stuff under lock and key. Betty continues to subtly display her newfound ability to assert herself in the partnership as she takes the drink Don just poured for himself, and there's another reason Don's going to seek out an unpopulated bar later on.
Sally's reading to Gene from The Decline And Fall Of The Roman Empire, and that may not be the most subtle way to foreshadow all the coming upheaval this season, but she is just a kid. But while I'm at it, I think I see better what this season is about now; it's not merely looking at people's attitude toward change but at their ability to say goodbye and to move on from great loss, the most cataclysmic example coming (I don't think I'm spoiling anything here, since they pointed to it so dramatically last episode) with the JFK assassination at, I'm guessing, the end of the season. Anyway, Sally is at least reading, if not learning, an awful lot of SAT words, but Don interrupts the vocabulary session (and description of Antioch being a hedonistic and shallow society) to inform Sally that it's time for bed. Gene, after implying that Don's vain and focused on pleasure by asking him how Babylon is, dismisses her with an admonition to "wash [her] teeth," and I'm not sure whether that's a regionalism, a dated expression, or another example of the fact that Gene ain't quite right anymore. If he'd only added a reminder for her to brush her face, I'd know it was the last. Regardless, Sally hands him the book; referring to what's coming in the story, presumably, he tells her "all hell's gonna break loose." Well, it is a historical text. That's a pretty good bet.