Some modern scholars believe that the Church in the early stages picked up pagan oral teachings from Palestinian and Hellenistic sources, which formed the basis of a secret oral tradition, which in the 4th century came to be called the "disciplina arcani". Mainstream theologians believe it contained liturgical details and certain other pagan traditions which remain a part of some branches of mainstream Christianity (for example, some Catholic theologians thought that the doctrine of transubstantiation was a part of this). Important esoteric influences on the church were the Christian theologians Clement of Alexandria and Origen, the main figures of the Catechetical School of Alexandria.