When Rome was first founded it was surrounded by wilderness, and packs of wolves roamed over the countryside. Among their many gods, the Romans had one named Lupercus who watched over the shepherds and their flocks. In his honour they held a great feast in February of each year and called it the Lupercalia. On the calendar used back in those days, February came later than it does today, so Lupercalia was a spring festival. Some believe the festival honored Faunus, who like the Greek Pan, was a god of herds and crops, but the origin of Lupercalia is so ancient that we'll probably never know for sure.
Lupercalia was an important celebration. Each year, on 15th February, a number of rituals were performed, some of which involved youths of noble birth running through the streets with goatskin thongs (!!). Young women would crowd the street in the hope of being lashed with the sacred thongs (!!!) as it was believed to make them better able to bear children. The goatskin thongs were known as the februa and the lashing the februatio, both coming from a Latin word meaning to purify. The name of the month February comes from this meaning.
Long after Rome became a walled city and the seat of a powerful empire, the Lupercalia lived on. When Roman armies invaded France and Britain, they took the Lupercalia customs there. One of these is believed to be a lottery where the names of Roman maidens were placed in a box and drawn out by the young men. Each man accepted the girl whose name he drew as his love - for a year or longer. Pope Gelasius the First decided to change the lottery and have the names of both young men and girls put into the box and drawn out in pairs. Each couple exchanged gifts. The girl became the man's valentine for that year. On his sleeve he wore her name and it was his bounded duty to attend and protect her. This custom of drawing names took place on the 14th of February, the day on which St Valentine was celebrated, and was considered a good omen for love. It often foretold a wedding.
And so Valentine's Day was born - a lovers' day, a time for loving, for giving and receiving love tokens.
Hallmark took over much later, after British settlers had imported Valentine's Day into North America during the 19th century.
Many thanks go to Gigi whose blog gave me the idea (and some of the information) for this entry.