Valentine's Day may seem awash in saccharine, wine, and roses, but its origins are darker than its modern-day Hallmark reality—they lie partially in the pagan Roman celebration of Lupercalia, a fertility festival wherein bachelors sacrificed a goat and dog, ripped the skin off, and whipped women with them. Women would line up to be hit, NPR reports, because they considered it good luck for fertility. The guys would draw a name out of a jar, and couples would pair off for the duration of the festival, which lasted from February 13 to 15.
Later, in roughly 300 AD, Emperor Claudius executed two men named Valentine on February 14, which is the namesake and date of the Valentine's celebration. However, the link to romance comes from Pope Gelasius combining the tradition of Lupercalia—which had outlasted the pagan religion that created it—with St. Valentine's Day in order to neuter the pagan festival. "It was a little more of a drunken revel, but the Christians put clothes back on it," says a UC Boulder historian. "That didn't stop it from being a day of fertility and love." Click for a NASA probe's Valentine's Day plans.