I would be researching seventeenth-century garden design or I would be doing something with Pepys, but I just kept using all of it to write about Margaret Cavendish. It took me a long time to realize that I just wanted to write a book about her. Years.

There was a stage inside it and a crank on the outside that would rotate something, like a tiny tree carved of cork, onto the stage, and then the thousands of little mirrors would multiply that one tree so that the viewer would see an infinite forest instead.

I suppose also that watching marketing and publicity stuff play out from behind the scenes, making those plans and seeing each piece fall into place or not, each year, for each book, has made me a little more tranquil about the process for my own book than I might otherwise be.

Margaret Cavendish was one of the people who came up in the course. That was when I started thinking about her as a character for a book, but my idea was for a totally different book. It had all these characters in it; Samuel Pepys was one of the main characters. He famously wrote these extensive diaries through the period that are really funny and sort of saucy, actually.

So it was this multi-perspective, multi-character book, and it went through all of these different manifestations. I'm not sure there was a single moment where I thought to myself, Oh, I need to write about Margaret Cavendish. She just kept taking over the book I thought I was writing.

I sense people expect something to show for ten years. But I do feel like it is dense. Some of my own favorite books are slim, but there's a lot of weight and power in them.

But when I realized it was actually going to be this portrait of the artist, birth to death, I had to then discover who Margaret as a young woman would be. I had to find the different voices for her throughout her life. I had a lot of fun discovering that. I had a lot of fun writing the childhood sections. By imagining her childhood, I was able to come up with this voice that matures as she gets older.