In the time of Chaucer, it’s said that (love) birds began their annual search for a mate around February 14.

Trusting in the Goddess Venus, on February 14 the amorous young men of ancient Rome drew the names of eligible young ladies who they would then court during the year. 

Into this pagan love lottery, horrified Christians substituted names of saints to be imitated during the coming year. Not much fun in that, is there?