Saint Valentine, the Martyr

According to the 1962 Missal of Saint John XXIII the Extraordinary Form of the Roman Rite, February 14th is the feast of Saint Valentine. He was a priest of Rome, (some sources say he was even a bishop), who was beheaded in about 273 A.D. 

Pope Julius I built a basilica on the Flaminian Way, believed to be the site of his martyrdom.

Greater love hath no man than that he lay down his life for his friends. (Jn1:13)

During the time of Claudius II, a decree was issued which forbid marriage. Saint Valentine defied this decree and urged young lovers to come to him in secret so that he could join them in the Sacrament of Matrimony. Eventually he was discovered by the Emperor, who had Valentine arrested and imprisoned. 

Saint Valentine held steadfast in his Faith and in turn attempted to convert Claudius to Christianity, at which point the Emperor condemned him to death.

While in prison, Valentine was tended by the jailer Asterius, and his blind daughter. Asterius' daughter was very kind to Valentine and brough him food and messages. They developed a friendship and toward the end of his imprisonment, Valentine was able to convert both father and daughter to Christianity. Legend has it that he also miraculously restored the sight of Asterius' daughter. 

The night before his execution, the priest wrote a farewell message to the girl and signed it affectionately, "From Your Valentine," a phrase that we still use today. He was executed on February 14th, in Rome.

The Martyr, not the Cherub with arrows

The association of Saint Valentine with pink hearts, boxes of chocolates, and the exchange of romantic fancies has no intrinsic source in the character or life of the saint. The origin of Saint Valentine's Day ~ a day beloved of greeting card companies ~ is not entirely clear, but it seems to have taken root in England, a cold country where the signs of spring are eagerly anticipated. As far back as Chaucer it was commonly observed that birds began to pair and mate around the feast of Saint Valentine, that is, from the middle of February.

In any case, the Valentine whose name is oddly commemorated was apparently a Christian priest in Rome who assisted (other) martyrs during the persecution under Emperor Claudius II. He was eventually arrested and sent before the prefect of Rome. When he refused to renounce his Faith, he was beaten and beheaded.

Thus, by offering his heart, he proved himself a true devotee of the God of Love.

Sources: 
(1) ALL SAINTS by Robert Ellsberg
(2) catholicculture.org