That which “circles around.” The term is applied especially to epistolary literature: Paul's letter to the Ephesians represents the earliest example within Christian documents: his statement in Colossians 4:16 provides explication of both intention and operational mode. In the subsequent generation several of the documents now grouped under Apostolic Fathers were similarly intended, and thereafter any of the letters of a bishop to his church. Modern terminological usage distinguishes churchwide teachings of the bishop of Rome.