Disembark from an elevator onto Bergdorf Goodman’s third floor, turn to your left, and walk down a narrow, dressing-room-lined hallway. At its end, in an airy, cream-colored office filled with orchids, framed photographs, and just one clothing rack, you’ll find Betty Halbreich, the department store’s first personal shopper and one of its oldest employees. She sits in a cream-colored chair at a cream-colored desk, with her completely filled planner open before her. Emily, her assistant, sits on the other side of the room. “We stay in our own worlds, and we co-exist,” Betty says, looking over at Emily. Emily pauses her typing, and laughs.

Halbreich says, of her morning routine, “I’m here very early, with the stock people, with the cleaning people, and it’s wonderful.” By ten o’clock, on most days, she has walked through and picked over the second, third, fourth, fifth, and sixth floors, “when everything looks so fresh.” She culls from the entire store for her clients. “And that surprises people. But, you know, I really don’t believe you should be stamped. ‘Oh, she’s wearing Joe Blow’s clothes,’ or, ‘She’s wearing Joe Moe’s.’ People always say ‘What are you wearing?’” She feigns looking herself up and down. “Really? I can’t even tell how many different people I have on. That’s what personal shopping should be.”

Ira Niemark, Bergdorf’s C.E.O, hired Halbreich in 1976. Her memoir was published this summer; Lena Dunham and HBO are turning it into a television show. She has witnessed “the start of casual Friday, which was the beginning of the end”; the emergence of “those ankle-baring, rolled-up pants, no socks,” on men (eye roll); and, among countless other trends, our increasing obsession with youth: “I don’t understand it. I think old age is beautiful, and gracious.” She suffered in her twenties, she says; she’s not suffering now. “People want to hear from you, from what you’ve learned. Going from infancy, to youth, to middle age … isn’t that what it’s all about? Isn’t that why we were put here?” Halbreich pauses, her lips curling into an ever so slight smile, her eyes flashing mischievously. “I’d have to go into analysis to figure that one out.”

Visit the New Yorker video channel, featuring profiles, commentary, interviews, and more.