full effect on Christian thought when, in the thirteenth century, "a genuinely philosophic intellect, trained by a full study of the greatest Greek thinker, undertook to give complete scientific form to the ethical doctrine of the Catholic Church."[1] In the system of Thomas Aquinas the notion of law occupies a highly prominent, if not the first, place. It was the influence of Aristotle, doubtless, that led him to give the first place to the doctrine of goods and virtues. The most complete statement of his moral philosophy is found in the first part of the second division of the Summa Theologica. He begins with a discussion of the chief good, which he finds to be the blessedness of union with God. He next treats of the virtues, and, following "the philosopher," divides them into intellectual and moral. The moral virtues, again, are classified into the natural or acquired and the theologic or instilled. Those virtues which may be acquired by the natural man are the four cardinal virtues of the Greeks,—Prudence, Temperance, Fortitude, and Justice. Besides these, as necessary to the highest end of man (communion with God), there are the three theologic virtues which are instilled in man by divine grace,—Faith, Hope, and Love. This analysis of the virtues is followed by a subtle discussion of sin, and then the subject of law is taken up.
Thomas defines law as "an ordinance of reason for the common good which is promulgated by him who has charge of the community."[2] Four kinds of law are distinguished,—eternal, natural, human, and divine. The eternal law is the divine reason of the supreme governor of the universe by which all creatures, rational and irrational, are ruled. This law, in so far as it applies to rational creatures, is given to them in two ways,—naturally and by special revelation. Hence the two kinds, natural and divine, corresponding to these two modes by which the law is made known to men. A portion of the eternal law God has so implanted in men's minds as to be known by natural reason. This is natural law, or the law of nature. All rational action aims at some good. The first principle,
