Diana, Princess of Wales, was lucky to have only three people in her marriage; King Solomon needed 300 mistresses to keep him happy.
Married life might be less crowded today than it was at the start of the previous millennium, but the mistress has by no means disappeared. In Mistresses, Elizabeth Abbott looks at 80 'other women', from Greek concubines to Camilla Parker Bowles, and asks why they chose to live in the margins of someone else's life. We all know what men get out of the deal, but what's in it for the mistress?
The answer is usually money. Financial support is "integral to mistressdom, indeed one of its most attractive features". The late Sir James Goldsmith observed that a man who marries his mistress creates a vacancy: mistressdom is a profession, replete with perks, promotions and -- all being well -- a pension.
For 40 years, Marion Davies was swathed in mink and charmed with champagne by the newspaper mogul William Randolph Hearst, who kept his wife on the east coast and his mistress on the west coast. 'May I be a mother to you?' he asked Marion. She would have preferred him to be a husband, but settled for calling him 'daddy' instead.
As in any career, it is not necessary to be in love with your boss in order to excel at the job, and many mistresses, Abbott suggests, don't much like the men who pay their rent. Judith Campbell, who juggled simultaneous affairs with John F Kennedy and the mobster Sam Giancana, preferred power to personality, which was just as well given that Giancana, who oversaw an empire of more than 50,000 criminals, had been rejected by the US Army as a 'constitutional psychopath'.
JFK, meanwhile, kept a harem (including at one point Marilyn Monroe) to satisfy his daily demand for a stress-releasing ejaculation. Sex with the president, said another of his mistresses, the actress Angie Dickinson, constituted 'the most memorable 15 seconds of my life'.
Mistresses presents itself as a cultural and historical survey, taking in the likes of geishas, harems, clerical mistresses and the captured slaves of Spanish conquistadors, but it is closer to being an encyclopedia of sexual disappointment.
"So many mistresses," Abbott writes, "so many stories!". And so little difference between them all. While Abbott stresses that no two mistresses have had the same experience, the cumulative effect of placing their tales next to one another is to show how they can be reduced to the same pattern: man gets all of woman, woman gets half of man. As Joanna Trollope puts it in Marrying the Mistress: "We sleep together, you pay for some things for me, I keep myself exclusively for you. That's what they do, mistresses."
Sometimes this arrangement works for the woman, but more often, as with Maria Callas and Aristotle Onassis or Lady Caroline Lamb and Byron, it does not.
What is striking about these brief biographical 'case studies' is not only how similar they are but how fictional they seem. As a type, mistresses have never come across as being quite real -- at least not as real as wives -- and Abbott suggests that it is the desire to live like a novelistic heroine, or one of the famous mistresses of the past, that attracts many women to the role in the first place. After all, Parker Bowles introduced herself to Prince Charles by reminding him that her grandmother had been the mistress of his grandfather, and even novelistic heroines want to live like novelistic heroines.
It was reading romances that turned Emma Bovary from a potentially happy housewife to a woman who, as Flaubert puts it, gasps for love as a carp on a kitchen table gasps for water.
A section of Mistresses is devoted to the great fallen women of literature, Anna Karenina, Hester Prynne, and Lara in Dr Zhivago. Even Jane Eyre herself, Abbott reminds us, only narrowly missed such a fate. "That man had nearly made me his mistress," Jane says of the bigamous Rochester. "I must be ice and rock to him".
"Hiring a mistress," Rochester agrees, "is the next worst thing to buying a slave".
Abbott increasingly agrees with Rochester, and she tells the stories of mistresses known to her personally who have not moved with the times. The sexual revolution has passed them by, she laments in a matronly tone; instead of enjoying the freedom of their position, most of today's mistresses are "casting themselves in the ancient mould", dedicating themselves to lives of "sacrifice and sadness".