When I was in grad school, a friend told me I would get a kick out of this book she was reading, Sex with Kings. And I really did. It was most edifying. In fact, I want to reread it, and I wouldn't mind owning a copy. I'd never thought much about royal indiscretions, but I learned a lot about royal life (and loneliness) from Herman's book. And since reading this, I've heard a lot of references to famour mistresses, like Madame Du Barry, who is one of the most famous royal courtesans ever. As I recall, the book only covers some of Europe's kings and their mistresses, and it opens the path to more research for other scholars.* Because it's a scholarly monograph, it does get a little repetitive; good for researchers who will read only a chapter or two, but not as much fun for casual readers who just sit down and read it cover to cover. The non-chronological jumping around makes it a little harder to keep track of which mistress goes with which king and the time frames of all the reigns, so I highly recommend keeping a little notebook to jot down names and years--it may sound like a little more work than you tend to do when reading, but such notes will be very helpful. A must-read for you fans of Phillippa Gregory and other royalty-based historical fiction. *Herman has also written Sex with the Queen, which I'm adding to my wishlist right now.