In the first few centuries Christians turned to natural law in the context of the broadly based intellectual movement by which they interpreted the Christian revelation in the categories of Greek philosophy. Morality too benefited from the influence of the Greek thinkers. The task of educating the early Christians to the demands of the new morality, and persuading them to break out of the straitjacket of the Old Covenant was possibly the most serious problem which St Paul had to contend with during the whole of his apostolic mission. Up to the middle of the twentieth century, the basis of Catholic morality was presented as obedience. From an early stage in the Church’s history, Christians were searching for something a little more precise to guide their conduct, over and above the general moral orientation that they took up when they pledged faith in Jesus.