Was her relationship with David really as rosy and equal as it seemed?

"I think they really loved each other and that they had a very modern marriage in some ways. She used to write about the fact that she would come home from work and cook him dinner and play the wifely role‚ and maybe she did, though you have to imagine they had a cook.

"But I do think they had a very modern marriage in that she went to work every day and so did he, and he supported her and she supported him. They were very equal in that sense. But he also absolutely helped launch her career: He had been an editor at Cosmo, early in his career. He came up with the idea for Sex and the Single Girl, he shopped it around, he helped get it into the right hands. When she was at Cosmo, he wrote all the cover lines and he read all the articles, or many of them. So he had a lot of say."

That seems like a highly evolved definition of marriage for the time — the idea that you get to choose what you want it to look like.

"Yes. When she married him, she was 37-years-old. This is part of what’s at the crux of her philosophies: She spent her twenties and thirties dating around, working her way up her career ladder. She was already extremely successful as an ad copywriter and an account executive when she and David met. She already had a Mercedes, which she bought with her own money — and that’s one of the reasons he fell for her in the first place.

"He wanted a woman like that: successful and ambitious. He liked that about her. That was already part of the package. So that was the advice that she gave to her Cosmo girls: Don’t settle down at 22. The mentality at the time was get married, have kids, and stay home — and that’s fine. But she was telling young working-class girls: Get a job, turn it into a career, work really hard, date around, make something of yourself, be independent.

"When I read Sex and the Single Girl for the first time, 50 years after the publication, I thought it was so funny and charming. Despite all the ridiculous advice that she gives, she also was talking to women about budgeting and jobs and how to get ahead and save money. A lot of that book still felt relevant and certainly ahead of its time."

Helen got a bad rap from feminists for a long time. When do you think that started to change?

"I think the farther we get away from the '60s, the less harshly we feel the need to judge her because we’re looking at her in context of an era.

"Think of it this way: HGB is older than your grandma. You see her within the context of her era, if you know who she is at all, and that’s my question: How many young women know who she is? I’m not trying to hold her up as an example of some great feminist leader at all. That’s not my concern or my interest. But I will say that I learned so much about feminism through reading about her."

What is one big thing you wanted to show readers about Helen Gurley Brown in the book?

"Her story really does speak to the human condition and to identity. The themes of what drove her are very universal, and that’s why Cosmo resonated so deeply with readers, because it’s so human: to want to be beautiful, to want to be loved, to want to have not just money but security, to want to be known."

To have it all.

"Yes! To want everything."