Cicero's exposition of the doctrine of a natural law on the Stoic model and the various definitions of the natural law that found their way into the Roman law constitute important strands in the developing tradition. They are joined by another strand which, although not invariably distinct from them, is nonetheless of the first importance. It will be useful to consider the Christian contribution to the growing insistence upon the natural law first of all in the New Testament, particularly in St. Paul, and then in the Fathers and the ecclesiastical writers of the early Christian centuries.