Father Pegues concludes his exposition of St. Thomas Aquinas’ teaching on law by discussing a fourth type of law: the divine law.
The divine law is “the law given to men by God who manifests Himself supernaturally. God gave this law to men in the first place in a very simple way before their fall in the Garden of Eden; but He also gave it in a much more elaborate way, later on, through the medium of Moses and the Prophets, and in a way much more perfect by Jesus Christ and the Apostles.” The divine law given by God to men through Moses is called the Old Law, and the divine law given by God to men through Christ and the Apostles is called the New Law. God gave the Jewish people a special law “because this people was destined to prepare in the old world the coming of the Saviour of men who was to be born of the Jewish nation.”
The judiciary and ceremonial precepts of the Old Law were intended only for the Jewish people, whereas the moral precepts in the Old Law were carried over into the New Law. These moral precepts “constitute what is essential and absolutely obligatory concerning the conduct of every man.” They have “always been and always will be the same for all men.” They are identified with the natural law and are part of the divine law. “God Himself promulgated them solemnly when He manifested Himself to His chosen people at the time of Moses.” These moral precepts are called the Decalogue, the Ten Commandments.
Do the Ten Commandments suffice to guide a person in the way of virtue? “They suffice as regards the principal virtues which have reference to the essential duties of man towards God and his neighbour; but for the perfection of all the virtues it was necessary for them to be further explained and completed by the teaching of the prophets in the Old Law, and still further by the teaching of Jesus Christ and the Apostles in the New Law.”
In the New Law, “the counsels are added to the precepts.” The counsels are “certain invitations offered by Jesus Christ to all souls of good will, to detach themselves from earthly things for love of Him and in order to obtain a more perfect enjoyment of Him in heaven, things that they might indeed desire and possess without detriment to virtue, but which might prove an obstacle to the perfection of virtue.” There are three counsels: poverty, chastity, and obedience. A person may practice these counsels in a very perfect way in the religious state of life.
Quotations from Thomas Pegues, Catechism of the “Summa Theologica” of Saint Thomas Aquinas, trans. Aelred Whitacre (New York: Benziger, 1922).