Panel 1: That night, we find John and Elly in bed. He tells her that he can't believe how much he's enjoying his electric train set.
Panel 2: He says a rather obvious thing that I've known ever since he started coveting his kids' Christmas bounty when he says that there's this little kid in him that's just wanted to play again.
Panel 3: He comes to the conclusion that no matter how old we are physically, we never really grow up. When he asks if that's a silly thing to say, she says no, it isn't.
What she doesn't tell him is that her mother says she's still waiting to feel like an old person.
Panel 4: She just implies that someone older said the same thing when she hugs him and tells him that he just has to be mature enough to admit it.
Summary: This is the part of the sitcom where they'd have the end credits and theme music. This is also something that contradicts what we saw and what is to come. Ah, well. Monday, we start years of Liz's insecurity about her appearance being dialed up to eleven when they finally realize that she's nearsighted and needs eyeglasses.