bubonic plague which had killed 100,000 French citizens. Desperate measures were called for to repopulate homes and refill palace tax coffers so a royal proclamation was issued called Proclamation royale de l'amour français which was posted around the country by hundreds of the court's finest scantily-clad ladies of the evening, singing an earlier version of "What is this thing called love?" Essentially, the pronouncement was designed to begin the first hippie "free love" movement. Love beads made from dyed kidney stones, small seashells and hand painted rocks were worn around necks, beards became fashionable and sandals were to be worn only without socks unless one wanted to run the risk of beheading by guillotine.
The male population were immediately interested. Seeing the eye-popping reactions of the local men to these ladies and the proclamation explaining and encouraging new feelings of intimacy between the sexes, (feelings until then normally reserved for inanimate objects like favorite chairs and fine wines) the wives and girlfriends of these men chased the Court Ladies out of town and began to sing themselves, write beautiful poetry and wore patchouli oil to smell better; causing men to look at women with fresh eyes. Men began to take out the garbage, have baths more than once a month and fixed things around the house. And love was born.
Before then, people had relations of course, but it was considered a messy, purely physical duty that included lots of grunting and splinters. Men and women didn't actually even like each other very much. Duties those days were firmly based on keeping men doing things that kept them away from what the women were doing. And women were just fine with that.
After the proclamation came out though, things changed. Knowing that this new thing called amour had royal approval falling in love became la nouvelle chose populaire – a national mania. Everyone wanted a piece of that action. In honor of the King's proclamation the act of encouraging love by one person to another was called la courtoisie, or "courting". And it took very few years for the population of France to regenerate itself back to pre-plague levels.
(All of the above is a total fabrication, of course. Everyone knows the Greeks invented everything...)