The ancient church orders form a genre of early Christian literature, ranging from 1st to 5th century, which has the purpose of offering authoritative "apostolic" prescriptions on matters of moral conduct, liturgy and Church organization. These texts are extremely important in the study of early liturgy and served as the basis for much ancient ecclesiastical legislation.
A characteristic of this genre is their pseudepigraphic form. Many of them profess to have been handed down by the Twelve Apostles, in some cases purporting to have been gathered by Clement of Rome or by Hippolytus of Rome. In the earliest of them, the Didache, extends to the title: The teaching of the Lord to the Gentiles by the Twelve Apostles. The later Testamentum Domini declares itself to be the legacy left by Jesus Christ himself to his Apostles before the Ascension, and to give his own words and commands as to the government of the Church. Apart from the Apostolic Constitutions, which was printed before 1563, all other texts have been discovered and published in the 19th or early 20th century.
