The origin of St. Valentine’s Day is an obscure one, in part because there were several Christian namesakes in the 3rd century who died as martyrs at about that time/on that day so many years ago. The vagueness of origin has also to do with Pope Gelasius I’s motive for declaring February 14 St. Valentine’s Day at the end of the 5th century: mid-February had, of old, been a period for pagan festivals celebrating the coming of spring, in particular of the Roman Lupercalia, a fertility feast. He wanted to replace a pagan festival with a Christian commemoration, choosing a Saint who could in some way be associated with the pagan occasion.

The Saint very likely in view was Saint Valentinus from Rome. He was killed by the Roman Emperor Claudius II Gothicus, so legend has it, for going behind his back and marrying young men, although the Emperor had decreed that all young men remain bachelors as this allegedly made them better soldiers. Another legend tells that while in prison, Valentinus taught and fell in love with the jailor’s daughter, to whom he wrote a farewell letter before his execution, signing it “From your Valentine”. Portrayed as a sympathetic, brave and romantic figure, St. Valentine had become a popular Saint in England and France by the Middle Ages, the patron saint of the engaged and married. His spiritual duties further included, among others, helping the epileptic and assisting the keepers of bees.

By the 15th century, it seems, St. Valentine’s Day had clearly become linked to romance and the celebration of (courtly) love. In 1537 Henry VIII officially declared February 14 St. Valentine’s Day. Its popularity spread and by the mid-18th century it was usual for friends and lovers in Great Britain and the United States to exchange handwritten notes or small tokens of affection. Improvements in printing technology led to the gradual replacement of written letters with printed cards, and cheaper postage rates contributed to the growing popularity of sending Valentine Cards.

Today, Valentine’s Day is widely celebrated all over the world. It has become the second-largest greeting-card selling holiday of the year (Christmas being in first place) and is enormously profitable for business. See for example Valentine’s Day by the Numbers.

Here are some further links that may be of interest to you:

Not all Victorian Valentine Cards were pleasing to the beholder:

Source: The Guardian, Royal Pavilion & Museums, Brighton & Hove

Note: In 1969, the Catholic Church decided to remove from its lithurgical calendar the feast of all the saints with a questionable history – St. Valentine among them. This has apparently not affected the celebrations on that day – there business goes on as usual.