from The Golden Legend1
Valentine comes from valorem tenens, one who perseveres in holiness. Or it comes from valens tiro, a strong warrior, one who fights for Christ. But a warrior is strong only when he remains unconquered, bravely attacks, defends himself valiantly, victory. And so Valentine was never conquered, for he never fled martyrdom; he attacked the idols in exterminating them; he defended, the faith in that he strengthened it; he carried off victory in that he suffered.
Valentine was a priest whose holiness was known to 211. The Emperor Claudius summoned him and said to him: 'Valentine, why dost thou not earn our good will by adoring our gods and putting away thy vain superstitions?' Valentine answered': 'Didst thou but know the grace of God, thou wouldst not say these things; and thou thyself wouldst turn away from these idols, and wouldst adore the God of Heaven!' Then one of the emperor's retainers said to Valentine: 'Dost thou dam to disparage the sanctity of our gods?' And Valentine replied: 'Your gods are but the wretched fabrications of men, and are sodden with uncleanness!' Claudius then said: 'If thy Christ is the true God, tell me the truth!' And Valentine made answer: 'The truth is this: that Christ is the only God, and that if thou believest in Him thy soul shall be saved, thy power increased, thine enemies put to rout!' Claudius, turning to those around him, said: 'Romans, do you hear how well and wisely this man speaks?' But the prefect protested: 'The emperor is being deluded! Must we therefore renounce what we have believed since we were children?' These words hardened the heart of Claudius, and he committed Valentine to a prince of his court, to be guarded as a prisoner in his house. When he had come into the prince's house, Valentine cried out: 'Lord Jesus, Thou Who art the one and only Light, shed Thy light upon this house, that those who dwell herein may know Thee for the true God!' Whereupon the prince said to him: 'Since thou proclaimest that thy Christ is Light, ask Him to restore sight to my daughter who is blind!' And if He does this, I shall do all that thou biddest.' Valentine prayed, from that hour the blind girl saw, and the whole household was converted.
But the emperor was not deterred, and ordered him beheaded. His martyrdom took place in the year of the Lord 280.
1. From: The Golden Legend of Jacobus de Voragine, trans. and adapted by Ryan, Granger and Helmut Ripperger. (Arno Press: Longmans, Green & Co) 1941. pp. 165-166.