A lection, also called the lesson, is a reading from scripture in liturgy.
The custom of reading the books of Moses in the synagogues on Sabbath is a very ancient one. Since the prophetic books were written after the books of Moses, readings from them began later, and were common at the time of Jesus. This element in synagogue worship was taken over with others into the Christian divine service, as may be gathered from passages in the gospels such as St Luke 4:16–20 and 16:29. During early Christianity, readings began to be made from the writings of the Apostles and evangelists as the New Testament canon developed. Mention of this is found within the New Testament itself, for example in Colossians 4:16 and in First Thessalonians 5:27.
The oldest manuscripts of the Gospels have marginal marks, and sometimes actual interpolations, which can only be accounted for as indicating the beginnings and endings of liturgical lessons.
From the 2nd century onwards references multiply, though the earlier references do not prove the existence of a fixed lectionary or order of lessons, but rather point the other way. Justin Martyr, describing divine worship in the middle of the 2nd century says: "On the day called Sunday all who live in cities or in the country gather together to one place, and the memoirs of the Apostles, or the writings of the Prophets are read as long as time permits" (Apol. i. cap. 67). Tertullian about half a century later makes frequent reference to the reading of Holy Scripture in public worship (Apol. ~9; De praescript. 36; De amina, 9).