Schaff, Philip. "The Two Ways." The Oldest Church Manual Called the Teaching of the Twelve Apostles. Second Edition, Revised and Enlarged. New York: Funk & Wagnalls, 1886, 18-22.
Schaff notes that the two ways, of life and death, was suggested in other places as well. He cites Jeremiah 21:8, Deuteronomy 30:15, Matthew 7:13-14, and, less specifically, 1 Kings 18:21 (Schaff 1886, 18). The concept is attributed to John the Evangelist in the "Apostolical Church Order." The Epistle of Barnabas also describes a Way of Light and a Way of Darkness (Schaff 1886, 19(. Schaff observes that Barnabas 18-20 is strongly parallel to Didache 1-6. Schaff's opinion is that the Didache preceded Barnabas (Schaff 1886, 20). The Two Ways concepts are also very clearly present in the 4th century "Apostolical Constitutions," as well as in Talmudic writings and even some pagan literature (Schaff 1886, 21). However, within the Christian literature alone do we find the motivation as love for God and man.