Section Iii.--_of the Immutability of the Natural Law_.

1. Besides printing, many methods are now in vogue for multiplying copies of a document. Commonly the document is written out with special ink on special paper: the copy thus used is called a stencil; and from it other copies are struck off. We will suppose the stencil to be that page of the Eternal Law written in the Mind of God, which regulates human acts, technically so called. The copies struck off from that stencil will be the Natural Law in the mind of this man and of that. Now, as all who are familiar with copying processes know too well, it happens at times that a copy comes out very faint, and in parts not at all. These faint and partial copies represent the Natural Law as it is imperfectly developed in the minds of many men. In this sense, and as we may say subjectively, the Natural Law is mutable, very mutable indeed. Still, as no one would say that the document had been altered, because some copies of it were bad, so it is not strictly correct to say that the Natural Law varies with these subjective varieties. Appeal would be made to a full and perfectly printed impression of the document, one that rendered the stencil exactly. The Natural Law must be viewed in like manner, as it would exist in a mind perfectly enlightened concerning the whole duty of man, and exactly reproducing in itself that portion of the Eternal Law which ordains such duty. Were such a mind to discern a natural obligation to lie differently at two different times, all the relevant circumstances being alike in both cases, and the moral solution different, then only could the Natural Law be held to have changed.

2. But this is clearly impossible. The conclusion of a geometrical theorem is a truth for all time. There is no difference here between a complicated theorem, having many conditions, and a simpler theorem with fewer. It is indeed easier for a few than for many conditions to be all present together: but the enunciation of the conclusion supposes all the conditions, whatever their number. The same in a practical manner, as in the stability of a bridge. The bridge that would stand in England, would stand in Ceylon. If it would not, there must have occurred some change in the conditions, as the heat of the tropical sun upon the girders. A point of casuistry also, however knotty, once determined, is determined for ever and aye, for the circumstances under which it was determined. The Natural Law in this sense is absolutely immutable, no less in each particular application than in the most general principles. We must uniformly pass the same judgment on the same case. What is once right and reasonable, is always right and reasonable, in the same matter. Where to-day there is only one right course, there cannot to-morrow be two, unless circumstances have altered. The Natural Law is thus far immutable, every jot and tittle.

3. No power in heaven above nor on earth beneath can dispense from any portion of the Natural Law. For the matter of the negative precepts of that law is, as we have seen, something bad in itself and repugnant to human nature, and accordingly forbidden by God: while the matter of the positive precepts is something good and necessary to man, commanded by God. If God were to take off His command, or prohibition, the intrinsic exigency, or intolerableness, of the thing to man would still remain, being as inseparable from humanity as certain mathematical properties from a triangle. Pride is not made for man, nor fornication, nor lying, nor polygamy [Footnote 14]: human nature would cry out against them, even were the Almighty in a particular instance to withdraw His prohibition. What would be the use, then, of any such withdrawal? It would not make the evil thing good. An evil thing it would still remain, unnatural, irrational, and as such, displeasing to God, the Supreme Reason. The man would not be free to do the thing, even though God did not forbid it. It appears, therefore, that the Divine prohibition, and similarly the Divine command, which we have proved (c. vi., s. ii., nn. 10, 11, p. 121) to be necessarily imposed in matters of natural evil and of naturally imperative good, is imposed as a hard and fast line, so long as the intrinsic good or evil remains the same.

4. There is, therefore, no room for Evolution in Ethics and Natural Law any more than in Geometry. One variety of geometrical construction, or of moral action, may succeed another; but the truths of the science, by which those varieties are judged, change not. There is indeed this peculiarity about morality, distinguishing it from art, that if a man errs invincibly, the evil that he takes for good is not formally evil, or evil as he wills it, and the good that he takes for evil is formally evil to him. (c. iii., s. ii., n. 7, p. 33.) So there is variation and possible Evolution in bare formal good and bare formal evil, as ignorance gradually changes into knowledge; and likewise Reversion, as knowledge declines into ignorance. Even this Evolution and Reversion have their limits: they cannot occur in the primary principles of morality, as we saw in the last section. But morality material and objective,--complete morality, where the formal and material elements agree, where real wrong is seen to be wrong, and real right is known for right--in this morality there is no Evolution. If Hannibal offered human sacrifices to his grandfather because he knew no better, and could not have known better, than to think himself bound so to do, he is to be excused, and even praised for his piety: still it was a mistaken piety; and the act, apart from the light in which the doer viewed it, was a hideous crime. An incorrupt teacher of morals would have taught the Carthaginian, not that he was doing something perfectly right for his age and country, which, however, would be wrong in Germany some centuries later, but that he was doing an act there and then evil and forbidden of God, from which he was bound, upon admonition, instantly to desist. [Footnote 15]

5. There are Evolution and Reversion in architecture, but not in the laws of stability of structure, nor in the principles of beauty as realized in building. A combination, ugly now, was not beautiful in the days of Darius. Tastes differ, but not right tastes; and moral notions, but not right moral notions. It is true that questions of right and wrong occur in one state of society, that had no relevance in an earlier state, the conditions of the case not having arisen. But so it is in architecture; there are no arches in the Parthenon. The principle of the arch, however, held in the age of Pericles, though not applied.

6. The progress of Moral Science is the more and more perfect development of the Natural Law in the heart of man, a psychological, not an ontological development. And Moral Science does progress. No man can be a diligent student of morality for years, without coming to the understanding of many things, for which one would look in vain in Aristotle's Ethics and Politics, or in Cicero, De Officiis, or even in the Summa of St. Thomas, or perhaps in any book ever written. New moral questions come for discussion as civilization advances. The commercial system of modern times would furnish a theme for another De Lugo. And still on this path of ethical discovery, to quote the text that Bacon loved, "Many shall pass over, and knowledge shall be multiplied." (Daniel xii. 4.)

Readings.--St. Thos., Supplement, q. 65, art. 1, in corp.; ib., q. 65, art. 2, in corp., and ad 1; Hughes, Supernatural Morals, pp. 67, 68, reviewed in The Month for August, 1891, pp. 542, 543.