The popular customs associated with Saint Valentine's Day undoubtedly had their origin in a conventional belief generally received in England and France during the Middle Ages, that on 14 February, i.e. half way through the second month of the year, the birds began to pair. Thus in Chaucer's Parliament of Foules we read:
...For this was sent on Seynt Valentyne's day
...Whan every foul cometh ther to choose his mate.
For this reason the day was looked upon as specially consecrated to lovers and as a proper occasion for writing love letters and sending lovers' tokens. Both the French and English literatures of the fourteenth and fifteenth centuries contain allusions to the practice. Perhaps the earliest to be found is in the 34th and 35th Ballades of the bilingual poet, John Gower, written in French; but Lydgate and Clauvowe supply other examples. Those who chose each other under these circumstances seem to have been called by each other their Valentines.