By a "Law" in physics no more can be understood than a deduction from a sufficiently large series of observed facts, establishing, from long and tearful and extensive observation, a uniformity of result in the same given circumstances. Some laws are said to be "empirical," which though derived from careful noting of invariably [{385}] recurring phenomena, enunciate no principle, or rationale, but merely the numerical result of observation. Thus Kepler's three laws of planetary motion, and Bode's law of planetary distances from the sun, are instances of law simply and confessedly empirical. Newton's law of gravitation is said to furnish the principle which is involved in Kepler's formula of details; because once Newton's law is admitted as governing planetary motion, what Kepler observed of the movements of the planets, can be deduced by calculation. It would be perhaps more philosophical, in the present state of our knowledge, to regard even the most apparently elementary and fundamental law as only empirical, and the ultimate principle as lying deeper than any known law. In this view, a law like that of Newton's demonstrating, would be said to lie only one step nearer the ultimate principle than the earlier and more empirical. Probably there is no ultimate principle nearer than the divine volition.
In fact, the law of gravitation is now regarded by philosophers as something short of the ultimate solution of material attraction and repulsion; they are groping their way, at this moment, to something more universal than that law, as may be gathered from the following observations of Sir J. Herschel: "No matter from what ultimate cause the power which is called gravitation originates—be it a virtue lodged in the sun, as its receptacle, or be it pressure from without, or the resultant of many pressures or solicitations of unknown fluids, magnetic or electric ethers, or impulses—still, when finally brought under our contemplation, and summed up into a single resultant energy, its direction is from many points on all sides toward the sun's centre." [Footnote 139]
[Footnote 139: Outlines of Astronomy, chap. ix. §490.]
Whence is this uncertainty about the probable nature of this force? Because, universal as it has been thought, it fails in certain circumstances, as in some electrical conditions, and within very small distances; when the relation of material particles to one another is one of repulsion, and not of attraction. Take another law, as it is called, that fluids will always rise as high as their source, and no higher. The phenomena of capillary attraction prove that this law does not hold in all cases. The chemical law of atomic combination is sometimes found signally to fail. Physical laws, therefore, like these, are good only as far as they go; there are limits to their application.
Why may not this be true in regard to the law which is said to militate against the doctrine of the blessed Eucharist? It may hold good for a thousand instances, and may fail in the next, like other physical laws; and that instance may be the very one of this revealed doctrine. Exceptio probat regulam is a sound rule in a certain sense; it tells the other way, however, when the absolute impossibility even of an exception is maintained in regard to any physical law.
But, in fact, we see that this law of relation between quality, or accident, and substance, is very uncertain in its application to many conditions of matter. Modern discovery has much diminished the number of the properties, or qualities, of matter; and has proved that even these are by no means constant in the same substance, nor always variable in different substances; so that one substance often looks to every sense, like another, wholly different; and "behaves," like it, in a variety of ways; while the same substance has sometimes more than one mode of appearance. There is, in fact, no law of uniformity between material substance and its properties; if there is any law on the subject, it is the other way; and the result of discovery seems clearly to demonstrate that we know absolutely nothing of the nature of substance.
VIII.
Closely connected with this view of law is the interesting subject is [{386}] throughout nature, but especially in the motions and temporary disturbances in the heavenly spaces, and which afford, in fact, the best evidence of the stability of the vast system of creation. A variation is observed in the ellipticity of the earth's orbit, for instance, of which one evident proof is the acceleration of the moon's motion round her primary; it might seem as if, at some vastly remote period in future time, the total derangement of our planetary system must ensue; but calculation has assured us that there is a point, far short of that, at which there will occur a change; and in the lapse of ages things will return to their original condition. Thus beyond an exception to law there is still Law existing supreme, regulating the conditions and the term of such exceptional existence. In a similar manner, the law of storms, as it is called, establishes the dominion of definite order even in the confusion and mad fury of the tropical hurricane; so definite, and so completely under the control of observed rule, that navigators are provided with certain instructions for evading the overwhelming force of those terrible visitations. We think of these cycles of apparent exception and departure from established order, in the physical world, when we hear objections made against this or that apparent anomaly in the spiritual and moral government of God; till the principles and laws of one government are proved wholly unlike those of the other, we imagine a secular variation not impossible in the one as it actually exists in the other; and we can endure even a temporary eclipse of the outward glory of his church, the prevalence of her enemies against her, for a longer or a shorter time; the exile of her chief pastor; the triumph of iniquity in her glorious capital; convinced that erratic trains of events like these are subject to law in the permission of him who governs as he made the universe of matter and of mind, by an act of his sovereign and omnipotent will.
IX.
From what has preceded, one or two general reflections occurred to an intelligent mind, somewhat to this effect. It seems that the horizon of science has never been long stationary, and is now opening wider then at any former period. Every science has passed through many strange phases of empiricism, before reaching the philosophical basis on which it now rests. All of them are disclosing facts and analogies undreamed of by our grandfathers. A very few years make a book on chemistry or physiology old and out of date. We are posting on to further knowledge; strange and unimagined relations between matter and matter, and still stranger between matter and mind, are no doubt awaiting the detection of future discoverers; our children, or their children, will know more than we. A single sentence of Professor Faraday's reflections on the subject of Allotropism, is sufficient to open a wide view of the possible career of science. "The philosopher ends," he says, "by asking himself the questions, In what does chemical identity consists? In what will these wonderful developments of allotropism end? Whether the so-called chemical elements may not be, after all, mere allotropic conditions of purer universal essences? Whether, to renew the speculations of the alchemists, the metals may the only so many mutations of each other, by the power of science naturally convertible? There was a time when this fundamental doctrine of the alchemists was opposed to known analogies; it is now no longer opposed to them, but only some stages beyond their present development." [Footnote 140]