As early as Tertullian (c. 160–c. 220) pastoral writers were appealing to the wisdom of historical experience in understanding soul care. He recognized that each historical layer of developing pastoral experience should be funded by previous layers: Earlier works are more fitted for the instruction of the soul than later ones which, for their part, had to submit to instruction by the earlier ones. (Tertullian, Testimony of the Soul, Ch. 5, FC 10, p. 142) Many ideas thought to be exclusively modern