The Christmas hymn "In dulci jubilo", also known in English as "Good Christian Men, Rejoice", dates back at least to the year 1328. In that year the German mystic Heinrich Seuse, an associate of the great Meister Eckhart, claimed that he had learned the song from dancing angels. "This dance," he wrote, "was not of the kind that are danced on Earth, but it was a heavenly movement, swelling up and falling back again into the wild abyss of God's hiddenness." Be that as it may, the hymn probably was already in existence by that time. Its most distinctive feature is its mixture of Latin and German in the text; texts are this type are charmingly designated by scholars as "macaronic." This macaronic text is an unusually elegant one that makes syntactic sense in both languages; the line "alpha es et O," often cryptic to those who sing the hymn, means "Thou art the alpha and the omega." The original hymn was monophonic - it consisted only of a single melody line. It became part of German tradition, modified slightly to conform to Protestant theology, and was given multipart settings by Praetorius, Bach, and other composers.