O King of the Gentiles, and the Desired of all, you are the cornerstone that binds two into one. Come and save mankind, whom you formed out of clay.
--Antiphon for Vespers, Dec. 22 
Today is the feast of Blessed Jacopone da Todi. 
"The first real outburst of Christmas joy in a popular tongue is found in Italy, in the poems of that strange 'minstrel of the Lord,' the Franciscan Jacopone da Todi (b. 1228, d. 1306)."
From the fourth through the thirteenth centuries, Christmas was in the hands of monastics. Their hymns were theological, "stately and severe". Ordinary people were illiterate, and their religion "was in many respects merely a survival of the old paganism thinly disguised."
But then Jacopone came along. "A wild, wandering ascetic, an impassioned poet, and a soaring mystic, Jacopone is one of the greatest of Christian singers, unpolished as his verses are. Noble by birth, he made himself utterly as the common people for whom he piped his rustic notes. 'Dio fatto piccino' ('God made a little thing') is the keynote of his music; the Christ Child is for him 'our sweet little brother'; with tender affection he rejoices in endearing diminutives—'Bambolino,' 'Piccolino,' 'Jesulino.' He sings of the Nativity with extraordinary realism.?"
Veggiamo il suo Bambino
Gammettare nel fieno,
E le braccia scoperte
Porgere ad ella in seno,
Ed essa lo ricopre
El meglio che può almeno,
Mettendoli la poppa
Entro la sua bocchina."
--from Christmas in Ritual and Tradition, by Clement A. Miles