We celebrate celebrate this the most day because until 1969, it was one of the many Saint's Days observed by the Catholic Church. The Valentine’s Day was intended to dedicate to the patron saint of romantic causes, who was St. Valentine.
Nowdays, Valentine’s Day has been allowed to continue as a holiday for everyone Although it was removed from the Church's calendar in 1969. The valentine’s day still has religious meaning in Roman paganism.
At the beginning, Christians saw Valentine's Day as a way to honor St. Valentine, of whom there were actually three. The Catholic Church recognizes three saints by that name, all who were martyred on February 14.
Based on many of historical resources, the St. Valentine the day is named for was, most likely, a priest in the 3rd century who performed secret marriages when the Roman Emperor Claudius II thought single soldiers were more likely to enlist in the army. That St. Valentine was imprisoned and executed on February 4, 270. It is believed he was responsible for giving the jailer's blind daughter back her eyesight, and before his execution, he sent herss a note saying, "From your Valentine." The phrase is still widely used on valentines today.
It wasn't until 1537 that St. Valentine's day was declared an official holiday. The King of England. Henry VIII, known for his ways of disposing of wives, declared February 14th a holiday. It was another century and a half before religious devotional cards became non-religious cards to reflect the change in the holiday. In 496 A.D., February 14, was declared in the name of St. Valentine by Pope Gelasius. It remained a Church holiday until 1969, when Pope Paul VI took it from the calender.
On February 14, the ancient Romans celebrated the Feast of Lupercalia in honor of Juno, the queen of the Roman gods and goddesses. Juno was also the goddess of womesn and marriage so honoring her was thought to be a fertility rite.
At the feast held the next day, the women would write love letters and stick them in a large urn. The men would pick a letter from the urn and for the next year, pursue the woman who wrote the chosen letter. This custom lasted until the 1700s when people decided their beloveds should be chosen by sight, not luck.
Data was taken from: http://www.coolquiz.com/trivia/explain/docs/valentine.asp
