The Lectionary is the book containing the readings for the Mass of the day. The daily Mass readings have two cycles (1 and 2). The Sunday readings are on a three-year cycle (A, B and C). There are also specific readings for a special Mass (funerals, baptisms, weddings, ordinations, feast days).
At a daily Mass, there is a first reading, a Psalm, and the Gospel reading. The first reading is usually from the Old Testament and mirrors essential points from the Gospel reading. (Remember: The OT prefigures the NT, and the NT fulfills the OT). The Psalm chosen has a thematic relationship to both the first reading and the Gospel. There is a harmony between these three readings.
Why do I love all of this? The readings are the same for every Mass in every church around the world. The passages are not chosen arbitrarily by the Pastor, the music director, or the liturgy director of a particular parish. We don't study Hebrews simply because a preacher decided that's what he wants to talk about this week. These passages were chosen and revised by committees of divine worship and correlate with the liturgical seasons of the year. For example, the Gospel readings during Lent focus on sin and repentance and conversion. It would be a little weird if we were reading about the birth of Christ while we should be focusing on the Passion, right? To me, it is a relief to have the guidance of the Church on which scriptures to read each day. It helps me to reflect on scripture in a way that I find more meaningful, connecting the Old and the New. #livinglent2
*Since so much of our faith intertwines, tomorrow, we will discuss the Liturgical Calendar.