Valentine's Day is named after Saint Valentine, a Catholic priest who lived in Rome in the 3rd century. There are many stories about St. Valentine and over time these stories grew into the legend we know today.
At the time of Valentine's life, many Romans were converting to Christianity, but the Emperor Claudius II was a pagan and created strict laws about what Christians were allowed to do. Claudius believed that Roman soldiers should be completely devoted to Rome and therefore passed a law preventing them from marrying. St. Valentine began to marry these soldiers in secret Christian ceremonies and this was the beginning of his reputation for believing in the importance of love.
Eventually, Valentine was found out and jailed for his crimes against Claudius. While imprisoned, Valentine cared for his fellow prisoners and also his jailer's blind daughter. Legend has it that Valentine cured the girl's blindness and that his final act before being executed was to write her a love message signed "from your Valentine." Valentine was executed on the 14th of February in the year 270.
It wasn't until more than 200 years later that the 14th of February was proclaimed St. Valentine's Day. By this time Rome had become Christian and the Catholic Church was determined to stamp out any remaining paganism. A pagan fertility ritual was held in February each year and the Pope abolished this festival and proclaimed the 14th of February Saint Valentine's Day, thus establishing this feast day on the Catholic Calendar of Saints.
The poet Chaucer in the Middle Ages was the first to link St. Valentine with romantic love. This was the beginning of the tradition of courtly love, a ritual of expressing love and admiration, usually in secret. This custom spread throughout Europe and stories grew about a High Court of Love where female judges would rule on issues related to love on the 14th of February each year. Historians believe that these meetings were in fact gathering where people read love poetry and played games of flirtation.