The earliest extant specifically Christmas hymns appear in 4th-century Rome. Latin hymns such as "Veni redemptor gentium", written by Ambrose, Archbishop of Milan, were austere statements of the theological doctrine of the Incarnation in opposition to Arianism. "Corde natus EX Parentis" ("Of the Father's love begotten") by the Spanish poet Prudentius (d. 413) is still sung in some churches today.[157]
In the 9th and 10th centuries, the Christmas "Sequence" or "Prose" was introduced in North European monasteries, developing under Bernard of Clairvaux into a sequence of rhymed stanzas. In the 12th century the Parisian monk Adam of St. Victor began to derive music from popular songs, introducing something closer to the traditional Christmas carol.
By the 13th century, in France, Germany, and particularly, Italy, under the influence of Francis of Asissi, a strong tradition of popular Christmas songs in the native language developed.[158] Christmas carols in English first appear in a 1426 work of John Awdlay, a Shropshire chaplain, who lists twenty-five "caroles of Cristemas", probably sung by groups of wassailers, who went from house to house.[159]
The songs we know specifically as carols were originally communal folk songs sung during celebrations such as "harvest tide" as well as Christmas. It was only later that carols began to be sung in church. Traditionally, carols have often been based on medieval chord patterns, and it is this that gives them their uniquely characteristic musical sound. Some carols like "Personent hodie", "Good King Wenceslas", and "The Holly and the Ivy" can be traced directly back to the Middle Ages. They are among the oldest musical compositions still regularly sung. "Adeste Fideles" (O Come all ye faithful) appears in its current form in the mid-18th century, although the words may have originated in the 13th century.