The roots of St. Valentine’s Day lie in the ancient Roman festival of Lupercalia, which was celebrated on Feb. 15. For 800 years the Romans had dedicated this day to the god Lupercus. On Lupercalia, a young man would draw the name of a young woman in a lottery and would then keep the woman as a sexual companion for the year.
Pope Gelasius I [492-496] was, understandably, less than thrilled with this custom. So he changed the lottery to have both young men and women draw the names of saints whom they would then emulate for the year (a change that no doubt disappointed a few young men). Instead of Lupercus, the patron of the feast became Valentine. For Roman men, the day continued to be an occasion to seek the affections of women, and it became a tradition to give out handwritten messages of admiration that included Valentine’s name.