From Dom Guéranger's The Liturgical Year.
The Church honours, on this fourteenth day of February, the memory of the holy priest Valentine, who suffered martyrdom towards the middle of the third century. The ravages of time have deprived us of the details of his life and sufferings; so that extremely little is known of our saint. This is the reason of there being no lessons of his life in the Roman liturgy. His name, however, has always been honoured throughout the whole Church, and it is our duty to revere him as one of our protectors during the season of Septuagesima. He is one of those many holy martyrs, who meet us at this period of our year, and encourage us to spare no sacrifice which can restore us to, or increase within us, the grace of God.
Pray, then, O holy martyr, for the faithful, who are so persevering in celebrating thy memory. The day of judgment will reveal to us all thy glorious merits: oh, intercede for us, that we may then be made thy companions at the right hand of the great Judge, and be united with thee eternally in heaven.
Iste sanctus pro lege Dei sui certavit usque ad mortem, et a verbis impiorum non timuit; fundatus enim erat supra firmam petram.
Præsta, quæsumus, omnipotens Deus, ut qui beati Valentini martyris tui natalitia colimus, a cunctis malis imminentibus ejus intercessione liberemur. Per Christum Dominum nostrum. Amen.
This saint fought even unto death, for the law of his God, and feared not the words of the wicked; for he was set upon a firm rock.
Let us Pray
Grant, we beseech thee, O almighty God, that we who solemnize the festival of blessed Valentine, thy martyr, may, by his intercession, be delivered from all the evils that threaten us. Through Christ our Lord. Amen.