Article — Vermeersch, Theologia Moralis
Article I: On Eternal Law
— I. Notion of eternal law. Eternal law is "the very reason of the government of things existing in God as in the prince of the universe" 1. It is the eternal determination of creative wisdom, which coheres by an undivided bond with the creative reason itself. Through it, all creatures, according to their nature, are ordered to their end. According to their nature: and therefore by physical necessity, if they are irrational; by moral necessity, if they are rational.
Insofar as it regards rational creatures, law places in God not only an ordering to the common good but also the decree of promulgating it, so that all the elements of law are present in God as in a legislator. Yet because law connotates an accomplished promulgation, and this supposes creatures, that law, before creation, is indeed causally complete, but terminatively incomplete. For more, cf. moral philosophy.
1 St. Th. 1, 2, q. 91 art. 1, c.
— What it comprises. That eternal ordering comprises both that hypothetical order congruent with the nature of things, which divine Wisdom necessarily conceives: the order of pure nature; and the higher and more perfect order by which divine Goodness, beyond the due of nature, decreed from eternity to order rational creatures to Himself: the order of elevated nature; and the most excellent order of all, by which divine mercy willed to repair in Christ the nature fallen in Adam: the order of repaired nature.