Charles Buck Theological Dictionary 
Among ecclesiastical writers, are portions of the holy Scriptures read in churches at the time of divine service. In the ancient church, reading the Scripture was one part of the service of the catechumen, at which all persons were allowed to be present in order to obtain instruction. The church of England, in the choice of lessons, proceeds as follows:
for all the first lessons on ordinary days, she directs to begin at the beginning of the year with Genesis, and so continue till the books of the Old Testament are read over, only omitting Chronicles, which are for the most part the same with the books of Samuel and Kings; and other particular chapters in other books, either because they contain the names of persons, places, or other matters less profitable to ordinary readers. The course of the first lessons for Sundays is regulated after a different manner: from Advent to Septuagesima Sunday, some particular chapters of Isaiah are appointed to be read, because that book contains the clearest prophecies concerning Christ.
Upon Septuagesima Sunday, Genesis is begun; because that book, which treats of the fall of man, and the severe judgment of God inflicted on the world for sin, best suits with a time of repentance and mortification. After Genesis follow chapters out of the books of the Old Testament, as they lie in order; only on festival Sundays, such as Easter, Whitsunday, &c., the particular history relating to that day is appointed to be read; and on the saints days the church appoints lessons out of the moral books, such as Proverbs, Ecclesiastes, &c., as containing excellent instructions for the conduct of life. As to the second lessons, the church observes the same course both on Sundays and week-days; reading the Gospel and Acts of the Apostles in the morning, and the Epistles in the evening, in the order they stand in the New Testament; excepting on saints' days and holy days, when such lessons are appointed as either explain the mystery, relate the history, or apply the example to us.