The Apostolic Fathers (Clement of Rome, Ignatius, Hermas, Polycarp, and Papias; and the authors of the epistle of Barnabas, the epistle to Diognetus, 2 Clement, and the Didache) form the literary link between the NT period and later Christian generations. From about 95 to 150 CE a number of epistles and treatises give an important insight into how the tradition was both preserved and developed. On the one hand, there are frequent quotations from the OT (LXX), but the doctrine of the ministry is in process of evolution: while the Didache suggests that sometimes prophets and teachers could preside at the Eucharist, Ignatius emphatically asserts the authority of the bishop. Clement of Rome (about 95 CE) has a definitely Trinitarian concept of God. Polycarp of Smyrna, writing to the Church of Philippi, appears to suggest that parts of the NT (gospels, 1 Peter, Hebrews, and certain of Paul's epistles) were being read aloud in the assemblies. The epistle of Barnabas, written in Alexandria about 125, uses allegory and typology in the interest of Christology. The Shepherd, written in Rome by Hermas about 125, consists of five ‘visions’ and at one time almost qualified for admission to the NT canon: both the Shepherd and the epistle of Barnabas are found in Codex Sinaiticus.