In The Golden Legend
The Legenda Aurea of Jacobus de Voragine, compiled about 1260 and one of the most-read books of the High Middle Ages, gives sufficient details of the saints for each day of the liturgical year to inspire a homily on each occasion. The very brief vita of St Valentine has him refusing to deny Christ before the "Emperor Claudius" in the year 280. Before his head was cut off, this Valentine restored sight and hearing to the daughter of his jailer. Jacobus makes a play with the etymology of "Valentine", "as containing valour".
Read more about this topic: Saint Valentine