Joan (Christina Hendricks) and Peggy (Elisabeth Moss) in “Mad Men.” (Michael Yarish/AMC)

This post discusses “Severance,” the April 5 episode of “Mad Men.”

Back in the fourth season of “Mad Men,” Joey Baird (Matt Long), a freelance artist who was working with the core staff of the ad agency at the heart of “Mad Men,” started sexually harassing office manager Joan Holloway (Christina Hendricks), making ugly remarks about her and drawing crude cartoons of her that he taped up around the office. Irritated on her behalf, Peggy Olson (Elisabeth Moss) reports the situation to their boss, Don Draper (Jon Hamm), who urges Peggy to fire Joey.

Peggy is excited to report her victory to Joan, but when she passes on the news as the two women ride the elevator downstairs together, she gets a rather different reaction than she expects. “Now everybody in the office will know that you solved my problem, and you must be really important, I guess….I’d already handled it. And if I wanted to go further, one dinner with Mr. Kreutzer from Sugarberry Ham, and Joey would have been off it and out of my hair,” Joan tells Peggy bitterly. “You want to be a big shot. Well, no matter how powerful we get around here, they can still just draw a cartoon. So all you’ve done is prove to them that I’m a meaningless secretary, and you’re just another humorless b—-. Have a nice weekend. Good night, Peggy.”

But 3½ seasons later, Peggy and Joan take a similar elevator ride after another incident of ugly harassment that leads them both to very different conclusions. If “Mad Men” is a series about how people — particularly Don, the protagonist — often fail to change, it’s also a show about how the long accumulation of insults and life experience can lead to someone becoming radicalized.

The meeting that precedes the elevator ride is brutal. Peggy and Joan have gone to pitch their partners at McCann Erickson on the idea of a store-brand pantyhose that they hope will bolster their faltering client, Topaz, which is losing ground to L’eggs. The McCann Erickson men target Joan with a barrage of sexual comments, many of which imply that Joan will end up having sex with their department store contact, Dan: “He loves redheads.” “Would you be able to tell him what’s so special about your panties?” “So you can pull them down over and over?” “Do you wear them, Joan?” “Why aren’t you in the brassiere business?…You should be in the bra business. You’re a work of art.” “Warm him up first. Send a basket of pears to Marshall Field’s. The one thing Dan likes is a nice pear.” It’s agonizing to hear, and it’s dreadful to watch the contrast between Peggy’s bland, chipper expressions and the dismay that begins to show at the corners of Joan’s lips and eyes.

The Joan of season four might have prized her ability to keep her cool throughout the meeting and to emerge with a business victory. And the Peggy of season four might have been in a snit. But time has passed, and their positions are reversed.  “I want to burn this place down,” Joan says when Peggy suggests they get lunch. But Peggy’s initial expression of sympathy quickly turns into another rancorous exchange, with Peggy, who knows Joan has experienced harassment throughout her career, encouraging her to toughen up.

Eventually, they reach the crux of their disagreement. “You can’t have it both ways,” Peggy lectures Joan. “You can’t dress the way you do and expect –” “How do I dress?” Joan cuts her off. “So what you’re saying is I don’t dress the way you do because I don’t look like you, and that’s very, very true.” Peggy, peeved and embarrassed, snaps back at Joan: “You know what? You’re filthy rich. You don’t have to do anything you don’t want to.”

When HitFix asked me last week to write predictions for the end of “Mad Men,” I joked that Peggy would join the National Organization for Women, while Joan would end up throwing her lot in with the more radical women’s liberation movement. It was a riff based in part on this scene, where Peggy adopts Joan’s old position and argues that women should push through difficult environments, and Joan suggests something even more expansive. It’s no longer enough to maintain her dignity in the face of insult. Joan doesn’t want to box up her sexuality even if she’s no longer using it professionally. She doesn’t want to be criticized for wanting to work even though she doesn’t have to.

If Peggy is advocating tolerance — even though her co-worker John (Trevor Einhorn) tells his brother-in-law that Peggy is “the kind of girl who doesn’t put up with things” —  Joan is craving transformation. I doubt she’ll end up underground or even in a consciousness-raising circle; “Mad Men” has always been a powerful reminder that the changes of the ’60s took place a little more slowly than we remember them in the historical imagination and that personal change takes time to set in. But Joan seems ready for change that goes deeper than a department store makeover.