The Revised Common Lectionary is a three-year cycle of Holy Scripture readings that follow the Sundays, festivals, and seasons of the Christian liturgical year. It was compiled in 1992 by the ecumenical Consultation on Common Texts to provide a balanced scriptural guide for weekly worship that ensures exposure to the main themes of Christian faith and worship. It is ecumenical in nature and overlaps heavily with the Roman Catholic lectionary.
Four texts are assigned for each Sunday and festival:
The first reading usually comes from the Old Testament but is replaced by a reading from Acts during the season of Easter
Psalm(s)
A reading from an Epistle or other New Testament writing
A reading from a Gospel (Matthew, Mark, Luke, or John).
The three-year lectionary cycle (A, B, and C) focuses on different portions of the Gospels in each year:
“The word mercy in English is the translation of the Greek word eleos. This word has the same ultimate root as the old Greek word for oil, or more precisely, olive oil; a substance which was used extensively as a soothing agent for bruises and minor wounds. The oil was poured onto the wound and gently massaged in, thus soothing, comforting and making whole the injured part. The Hebrew word which is also translated as eleos and mercy is hesed, and means steadfast love. The Greek words for ‘Lord, have mercy,’ are ‘Kyrie, eleison’ that is to say, ‘Lord, soothe me, comfort me, take away my pain, show me your steadfast love.’ Thus mercy… refer[s]… to the infinite loving-kindness of God, and his compassion for his suffering children! It is in this sense that we pray ‘Lord, have mercy…'”
-from the book Orthodox Worship by Benjamin D. Williams and Harold B. Anstall