Readers may be more familiar with the yearly Sunday pattern for the first season of the liturgical year:
93. Each Gospel reading has a distinctive theme: the Lord’s coming at the end of time (First Sunday of Advent), John the Baptist (Second and Third Sunday), and the events that prepared immediately for the Lord’s birth (Fourth Sunday).
The Old Testament readings are prophecies about the Messiah and the Messianic age, especially from the Book of Isaiah.
The readings from an Apostle contain exhortations and proclamations, in keeping with the different themes of Advent.
Even though Advent Sundays are on a three-year pattern, these themes are maintained in all three cycles. Gospels are assigned for the current liturgical (not calendar) year. At a glance, Fr Felix Just’s Advent table gives you a quick look at the Bible passages.
Daily Masses are on a one-year cycle. The traditional division at 16-17 December is maintained, as we see:
94. There are two series of readings: one to be used from the beginning of Advent until 16 December; the other from 17 to 24 December.
In the first part of Advent there are readings from the Book of Isaiah, distributed in accord with the sequence of the book itself and including the more important texts that are also read on the Sundays. For the choice of the weekday Gospel the first reading has been taken into consideration.
On Thursday of the second week the readings from the Gospel concerning John the Baptist begin. The first reading is either a continuation of Isaiah or a text chosen in view of the Gospel.
In the last week before Christmas the events that immediately prepared for the Lord’s birth are presented from the Gospel of Matthew (chapter 1) and Luke (chapter 1). The texts in the first reading, chosen in view of the Gospel reading, are from different Old Testament books and include important Messianic prophecies.
Note that the first reading from Isaiah drives the choice of the Gospel in early Advent–something of a rarity in the Lectionary. Once John the Baptist comes to the fore on the second Advent Thursday, you may hear a voice other than Isaiah’s in the first reading. And then the third part of daily Advent–the prophecies of the Messiah and the early infancy narratives begin on December 17th. Again, check Fr Just’s site for a table of readings.
Catholic Sensibility 