In his first apology (ca. 150–155 A.D.), Justin Martyr wrote an early account of ancient Christian worship, describing ancient practices regarding the sacraments and Lord's Day worship. It was written to an unbeliever, and therefore Justin does not assume that his intended reader—the Emperor Antoninus Pius (138–161)—knows anything about Christian worship. Moreover, while Pliny describes the worship practices of the Christians in Pontus, Justin describes the liturgical customs of the church in Rome. Justin lived and worshiped in Rome, but he didn't convert in Rome. He most likely converted to Christianity in Ephesus around 130 A.D. So he was familiar with the liturgical customs of both Western and Eastern Christians. It is also important to understand that Justin's account is descriptive not prescriptive. It is not a church order (e.g. Didache, Apostolic Tradition). It is simply a description of what Christians were already doing not what Justin thought they ought to do. https://vimeo.com/405980301