Section I. On Eternal Law

I. Notion of eternal law. Eternal law taken broadly, or insofar as it regards creatures both irrational and rational, is defined: "the reason of divine wisdom insofar as it is directive of all acts and motions" (St. Thomas, I-II, q. 93, a. 1). Taken more strictly, it is the reason of divine wisdom insofar as it is directive of human acts; or, as St. Augustine defines it: "the reason or will of God commanding that the natural order be preserved, forbidding that it be disturbed."¹ By the natural order is understood the order founded in rational nature.

¹ Contra Faustum, bk. 22, c. 27.

II. Existence of eternal law is clear from this: in God, as Governor of the whole human community, there must be admitted an ordinance or law by which he directs human beings to the end. But the aforesaid ordinance is eternal, since God conceives or establishes nothing in time. Therefore there exists in God an eternal law (St. Thomas, I-II, q. 91, a. 1).

III. Acts of eternal law. Eternal law either prescribes, or prohibits, or permits, or counsels. By prescribing and prohibiting it imposes duty, but by permitting and counseling it grants right. "For the force of law," says Leo XIII,¹ "since it is to impose duties and to grant rights, rests entirely on authority, that is, on the true power of establishing duties and describing rights." Again: "It is wholly understood that in the eternal law of God there has been placed the norm and rule of liberty." St. Alphonsus teaches the same: "Every law," he says, "is from God; every natural right is from God.... The will of God alone, as most holy, most wise, and most upright, is the sole source of every right, every order, every law, every rule and measure of honesty. And to this purpose tends this sentence of St. Augustine: Nothing is done which is not either commanded or permitted from the invisible court of the Supreme Emperor" (Dichiarazione del sistema, n. 18).

Corollary. Human actions, although taken physically they are logically prior to law, nevertheless taken morally, or insofar as they can be placed by right, whatever they are, are posterior to eternal law. And just as obligation flows from law, so also liberty, insofar as it constitutes a moral faculty or insofar as it is a right, is derived from law and therefore is posterior to law.

¹ Encyclical Libertas, June 20, 1888.