In the High Middle Ages, Geoffrey Chaucer, called the father of English literature, wrote a poem called Parliament of Foules (Assembly of Fowls) (c.1393).
It it he described how fowls, birds, chose their mates in mid-February:
“For this was Saint Valentine’s day, when every bird of every kind that men can imagine comes to this place to choose his mate.”
He made another mention in the final chapter of The Cantebury Tales:
“The book of the Duchesse; the book of Seint Valentynes day of the Parlement of Briddes (Birds).”