Chapter I. On Natural Law

Natural law, according to St. Thomas, is "the participation of the eternal law in the rational creature." If you unfold this definition a little, you will be able to say that natural law is a necessary divine command, manifested by natural light, commanding that right order be preserved, forbidding that it be disturbed. - For there exist essential relations of man to God, to himself, and to his neighbor; the complex of these constitutes the essential order, to the preserving of which God cannot not oblige the rational creature, because otherwise He would contradict Himself. Wherefore the author of natural law is God; the subject is the rational creature; the herald is the light of reason; the object, insofar as the law is prohibiting, is intrinsically evil actions, or actions which directly overthrow those relations; but insofar as it is commanding, the object is intrinsically good actions. The former, however, fall under precept at individual moments; the latter only then when, if they were not placed, that essential order would be violated. - Cf. St. Thomas, 1-2, q. 91, art. 2.

Question. Can the object of the law of nature sometimes be unknown?

Response. The primary principles of this law, for example, good is to be done, evil is to be avoided, do not do to another what you do not wish to be done to you, cannot be unknown by anyone. Likewise proximate conclusions, such as most precepts of the Decalogue, likewise cannot be unknown except either rarely or for a short time among the rude and children. But remote conclusions can be unknown, and often are unknown, as is clear from so many controversies which have always been agitated among the Doctors. Cf. St. Thomas, 1-2, q. 94, art. 4. - St. Alphonsus, nn. 170 and seq.; and de Consc. n. 8.