As I read this section I am struck by the repeated emphasis on penance and fasting that used to be associated with Advent. I think that some remnants of the fasting rules lasted up until Vatican II and I know that in the East this is still a penitential season.
The oldest document in which we find the length and exercises of Advent mentioned with anything like clearness, is a passage in the second book of the History of the Franks by St. Gregory of Tours, where he says that St. Perpetuus, one of his predecessors, who held that see about the year 480, had decreed a fast three times a week, from the feast of St. Martin until Christmas. It would be impossible to decide whether St. Perpetuus, by his regulations, established a new custom, or merely enforced an already existing law. Let us, however, note this interval of forty, or rather of forty-three days, so expressly mentioned, and consecrated to penance, as though it were a second Lent, though less strict and severe than that which precedes Easter.
Later on, we find the ninth canon of the first Council of Mâcon, held in 582, ordaining that during the same interval between St. Martin's day and Christmas, the Mondays, Wednesdays, and Fridays, should be fasting days, and that the Sacrifice should be celebrated according to the lenten rite. Not many years before that, namely in 567, the second Council of Tours had enjoined the monks to fast from the beginning of December till Christmas. This practice of penance soon extended the whole forty days, even for the laity: and it was commonly called St. Martin's Lent. The capitularia of Charlemagne, in the sixth book, leave us no doubt about the matter; and Rabanus Maurus, in the second book of his Institution of clerics, bears testimony to this observance. There were even special rejoicings made on St. Martin's feast, just as we see them practised now at the approach of Lent and Easter.