Readings from Scripture are part of every Mass. At least two readings, one always from the Gospels, (3 on Sundays and solemnities) make up the Liturgy of the Word. In addition, a psalm or canticle is sung.
These readings are typically read from a Lectionary, not a Bible, though the Lectionary is taken from the Bible.
A Lectionary is composed of the readings and the responsorial psalm assigned for each Mass of the year (Sundays, weekdays, and special occasions). The readings are divided by the day or the theme (baptism, marriage, vocations, etc.) rather than according to the books of the Bible. Introductions and conclusions have been added to each reading. Not all of the Bible is included in the Lectionary.
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