X. PHYSICAL LAWS.
THIS is a name commonly given: but the conception of it is not always just and distinct, because the philosophers of these days differ much in their doctrine about corporeal natures, and not a few of them, as if in despair of getting at the truth on that point, oscillate between different systems.
Law is a rule and measure of operations and law must proceed from reason, because reason alone can properly be a rule and measure. But that alone is not sufficient. Reason must have from Will the power of putting in motion; and therefore Law, which is commanded by Reason, presupposes Will. "Commanding," says St. Thomas, "is an act of reason, presupposing, however, an act of the will."{1} How the command is expressed he explains thus: "Commanding is essentially an act of reason: for when he who commands orders the commanded to do something, he intimates or threatens."{2}
Now ordering in the manner of intimation belongs to reason, which can intimate or denounce in two ways. It may intimate in the indicative mood, as when a man says to another, "You ought to do this:" or it may intimate by moving him to do the thing, saying in the imperative mood, "Do this." If it be asked what Reason it is that we may call the rule and measure of all created things, unquestionably the answer must be that it is the Divine Reason, which in union with the Divine Will is the rule and exemplar of the whole order of the Universe. The Divine Reason therefore must be considered as universal Law; and as It is Eternal, so must this law be eternal. "Granted that the world is ruled by divine providence," says St. Thomas, . . . "clearly the whole Universe is ruled by Divine Reason and therefore that rule of government in God as in the supreme governor of the Universe, has the ratio of law. And since the Divine Reason conceives nothing in time, it has an eternal conception, we must therefore say that such law is eternal."{3} We have, therefore, the eternal divine law which directs with supreme power the order of all created things, that by tending to their different ends they may be the created expression of the Divine goodness, not only in being but also in operating and thus there shines forth in the Universe the image of the Divine perfections, or that extrinsic glory for which the Creator ordered the created universe.
The law, being the rule and measure of the operations, must be applied to those beings that have to operate; for if it merely remained in the mind of the legislator, it would be to no purpose. "Law," says the Angelic Doctor, "is imposed as a rule and measure. Now the rule and measure is imposed by its application to the things regulated and measured."{4} This application varies according to the variety of things, which, if rational, participate of the eternal law through the light of reason, which reflecting naturally as a mirror, the very principles of that law, have therefore the proper name of natural law. If they are no more than sensitive, they participate of the eternal law, through the instincts impressed on their nature, which only amount to a knowledge of a term by imagination and a necessary tendency to reach it. If they are without any knowledge at all, they participate of the Eternal Law by means of a disposition in their nature which inclines them to a certain end. "Law, being a rule and measure," says St. Thomas, "may be found in two ways, viz., either in the regulator and measurer or in the regulated or measured. For that which participates of the law and measure is ruled and measured; and therefore since all things, being subject to Divine Providence, are regulated and measured by eternal law, as is evident from what has been said (Art. I.), it is evident that all participate somehow of the eternal law, seeing that from the impression of it they have their inclinations to their proper acts and ends. But rational creatures are in a more excellent way under Divine Providence, as being a participant of Providence by providing for themselves and others. Wherefore in them there is participation of the Eternal Reason, through which they have a natural inclination to their proper act and end: and such participation of the eternal law in rational creatures is called natural law. Hence the Psalmist, after saying (Ps. 4), Sacrificate sacrificium justiticiae, answers the question, Quis ostendit nobis bona? saying, Signatum est super nos lumen vultus tui, Domine; as if he had said that the natural light by which we discern what is good from what is bad, which belongs to the natural law, is nothing else than an impression of the Divine light in us. Hence it is evident that the natural law is nothing else than a participation of the Eternal Law in rational creatures."{5} And speaking of brutes, he remarks, that their participation, not being by the way of reason, cannot properly be called natural law. "Even irrational animals," he says, "participate of the Eternal Reason in their own way; but since rational creatures participate intellectually and rationally, therefore their participation is properly called law, because law is a thing that belongs to reason, as above stated.{6} But irrational creatures do not participate of it rationally; and therefore it is not called law, except by a similitude."{7}
And here we must notice particularly what the holy Doctor says about the participation of the Eternal Law in inanimate beings.
"It seems," he objects, "that contingent natural things (i.e., corporeal things without sense) are not under the Eternal Law: for promulgation belongs to law, as was said above{8} (but promulgation can only be for rational creatures, to whom something may be announced.) Therefore rational creatures only are under the Eternal Law, and contingent natural things are not under it." But this, he replies, is contrary to what is said in the Book of Proverbs, viii. 29: Quando circumdabat mari terminum suum, et legem ponebat aquis, ne transirent fines suos. And he says (in corp. artic.): "We must give one answer about the law of man, and another about the eternal law, which is the law of God; for the law of man does not extend beyond the rational creatures subject to man. The reason of this is, that law is directive of actions adapted to those who are under some one else; so that, properly speaking, no one gives law to his own actions. Whatever things are done about the use of irrational things that are subject to man, are done by the act of the man himself who moves them, because such things do not move themselves, but are moved, as we said.{9} Therefore man cannot impose a law on irrational creatures, however much they are subject to him, but on rational creatures subject to him he can, inasmuch as by precept or proclamation he impresses on their minds a certain rule which is a principle of action. And as man impresses by proclamation a certain interior principle of action on others who are subject to him, so does God impress on all nature its principles of action (imprimit toti naturae principia propriorum actuum); and therefore God is said to command all nature as is said in the Psalms (cxlviii. 6 ): Praeceptum posuit, et non praeteribit; and thus every motion and every action of all nature is under the eternal law. Wherefore irrational creatures are under the eternal law in another way" (not as rational creatures are); "for they are moved by Divine Providence, but not through understanding the Divine Precept as rational creatures do." And, in the answer ad primum, he says that "the impression of the intrinsic active principle on natural things is like the promulgation of law to man, for through the promulgation of the law a certain directive principle of human action is impressed on men, as was said." (in corp. art.){10}
From this we can see clearly what is meant by Physical Laws. For a law may be considered either as in the legislator, who is the measure and rule, or in the things measured and ruled by him. Considered in the legislator, the eternal law, as prescribing the order to be followed by rational creatures in their operations, directing them towards their due proximate ends, and through these to their ultimate end, is called Moral Law. As prescribing the order to be followed by irrational creatures, animate or otherwise, in the operations by which they arrive at certain terms and certain direct ends, it is called Physical Law. Considered in the things measured and ruled, the Eternal Law, as Moral Law, is the impress of the Eternal Reason made by mental light on rational creatures, so that in them are the principles of practical truth, as expressions of eternal principles in the Divine Mind: and according to whether those principles are derived from the essence of the things or from the free will of the legislator, that law is called natural or positive. As Physical Law it is the impress made by God on all irrational things, that these may tend in their operations to the ends intended by the Eternal Law and this impress is found in the disposition, instincts and qualities given them by God, by Whose power they are inclined and determined to operate in this or that way rather than in another.
This is what Physical Laws were universally understood to mean; and if the said principles of operation in irrational creatures are to be denied, one fails to see how we can do otherwise than deny the existence of any physical laws, unless we apply the name without any real meaning. As the moral order consists in disposing human actions by the rule of Moral Law existing in human reason, so does the physical order consist in disposing the operations of all irrational creatures by the rule of physical law found in the principles of operation that God communicates to them and therefore, since moral order cannot be without moral law, neither can physical order be without physical laws. Thus, if we reject the above-stated doctrines, we shall be led by logical necessity either to deny the physical order and harmony manifested in the triple kingdom of nature and in each individual thing therein, or, admitting it, ascribe the same to blind chance, or assert that God is not only the First Supreme and Universal Cause, but also the secondary, immediate and total cause. This last conclusion would involve the risk of falling into the error of those ancient philosophers who said that God is the soul of the Universe; unless, being driven further, we madly affirm, as in fact many do in these days, that God is everything, and everything is God.
And here let us make an end of the general exposition, wherein much will be found wanting as to the various natures of the corporeal universe, their proportions and operations and the many and different phenomena resulting from them. But our purpose is to make evident the constitution of inorganic substances. We have touched on some of their principal and universal properties, now and then speaking of animate creatures, so as to make the rest clearer, and shew the unity and beauty of the System that we call the Physical System. We shall now say why it is called so.
{1} la. 2ae Q. xvii. 1.
{2} Ibid.
{3} Summa, la. 2ae Q. xci. a. 1.
{4} Ibid. 1a. 2ae Q. xc. a. 4.
{5} Ibid. Q. xci. a. 2.
{6} Ibid., ad 3.
{7} Ibid., ad 3.
{8} Q. xc. a.4.
{9} Q. i. a. 2.
{10} ibid., xciii. a.5.