Saint Thomas Aquinas [Thomas of Aquin, or Aquino] (c. 1225 – 7 March 1274) was a philosopher and theologian in the scholastic tradition, known as Doctor Angelicus, Doctor Universalis. He is the foremost classical proponent of natural theology, and the father of the Thomistic school of philosophy, which was long the primary philosophical approach of the Roman Catholic Church. The work for which he is best-known is the Summa Theologica. One of the thirty-three Doctors of the Church, he is considered by many Catholics to be the Church's greatest theologian. Consequently, many institutions of learning have been named after him.
Aquinas distinguished four kinds of law. These are the eternal, natural, human, and divine law. Eternal law is the decree of God which governs all creation. Natural law is the human "participation" in the eternal law and is discovered by reason. Natural law, of course, is based on "first principles":
. . . this is the first precept of the law, that good is to be done and promoted, and evil is to be avoided. All other precepts of the natural law are based on this . .
The desire to live and to procreate are counted by Aquinas among those basic (natural) human values on which all human values are based. Human law is positive law: the natural law applied by governments to societies. Divine law is the specially revealed law in the scriptures.
