# God's glory in the heavens/The Stability Of The Solar System

Solar System.
XVIII. THE STABILITY OF THE SOLAR SYSTEM.
The solar system may be viewed as a machine, manifesting intelligent design. The mechanism of the sun, planets, and satellites, suggests, just as a watch, the idea of a Contriver. One of the most remarkable evidences of design, in the celestial machine, is the provision made for its stability.
Innumerable other laws of force, beside that of the inversed square, might be conceived but this is only ​one consistent with stability in a system subject to perturbations. If the law of gravitation varied according to the inverse cube, instead of square, the slightest disturbance would precipitate the planet on the sun, or cause it to fly off from its control. With the existing law of gravity, though a planet were pushed out of its course by an impulse from a comet, it would pursue its new orbit with undeviating regularity; the primitive disturbance would not have a progressive tendency. When, however, we contemplate a system of many planetary bodies, the mere law of gravitation does not by any means insure stability. The complexity of the scheme can at once be understood, when we keep in view, that any given body is attracted, not merely by the sun, but by all the other bodies of the system—and that these attractions are constantly varying, according to differences of distance and direction. The consequence is, that the planet, instead of describing the orbit which it would do if undisturbed, proceeds along a very complex and irregular line. A planet thus disturbed may be compared to a person making his way through a crowd. He is jostled at every step, and pushed out of the straight course he would otherwise pursue. Still his path may be determinate enough, though made up of innumerable irregularities. The planet has, in like manner, to thread its way through the perturbing influences of the other bodies of the system, and, therefore, pursues a disturbed instead of a regular course. ​The inquiry naturally suggests itself, Can such a system possibly remain stable?—must it not, at last, fall into inextricable confusion? Newton saw how the mutual attraction of all the bodies of the system would entail serious disturbance; but it was beyond the reach of even his powers of analysis to discover the compensation which insures safety. He, indeed, came to the conclusion, that it would be necessary for the hand of Omnipotence occasionally to interfere, in order to prevent the crash of worlds and the ruin of the system. The machine was conceived to be imperfect, and, therefore, to need readjustment. Some have held, that this view of the system forces upon us, more irresistibly, the conviction of a God than the admission of a self-adjustment; but, undoubtedly, the self-adjusting arrangement only enhances the wisdom of the Designing Intelligence. It exhibits one of the most wondrous adaptations of means to an end, and consequently forces upon us, more convincingly, the necessity of Divine contrivance. A somewhat parallel case is furnished by the steam-engine. Watt, by the contrivance of the governor, enabled the machine to regulate itself, and to dispense with the aid of the attendant in proportioning the supply of steam to the work to be done. The centrifugal balls of the governor, performing their work according to certain mechanical laws, only exalt our estimate of the mechanical genius displayed in the construction of the steam-engine. ​We ought, however, to keep always in view that, although parallel in some points, there is a wide difference between a machine executed by human hands and the mechanism of the natural world. In the one case, the machine may work independently of the contriver; in the other, the working of the machine is just the mode of the Divine operation.
We have, in the mechanism of the human body, a principle somewhat similar to the self-adjustment of the solar system. The body has been well styled a "self-mending machine." It is constantly subject to disturbances of its normal state by disease and accident, but it possesses a wonderful power of readjusting the disturbed functions, so that the stability of the system, or, in other words, life is preserved. We regard this self-regulating power as one of the strongest evidences of intelligence; and in the same light ought we to view the self-adjustment of the celestial machine.
The solar system is subject to incessant disturbance, but it is so adjusted that the irregularities never endanger its stability. When a rod is poised on the point of the finger, it oscillates from one side to the other, and the stability depends on the oscillations never going beyond a certain degree. In like manner, the orbits of the planets are subject to oscillations, but the stability of the system is insured by these oscillations being subject to a limit. The perturbations to which the orbits of planets are subject may be divided, in regard to ​kinds—periodic and secular. In the first kind, the perturbations are soon compensated, the oscillations being comparatively rapid. The latter are those in which the compensation is effected only after comparatively vast intervals of time. The former depend on the relative positions of the planets themselves; the latter, upon the positions of their orbits.
To illustrate the difference between periodic and secular inequalities, we may suppose the orbit of a planet to be represented by the margin of an oval or elliptical lake, whose surface is agitated by waves. The observer, standing on the margin, will observe the waves advancing upon the beach and then receding. Every advancing wave increases the length of the lake by a very minute quantity; but, then, it is shortened just as much by the receding of the wave. There is a complete compensation, then, in the period of each wave, and however long the observer watches, he will find that there is no advance made up the beach beyond a certain point. If we, however, conceive the lake to be affected by tides, there will not be a complete compensation in the case of each successive wave. If it is flood, then the recess does not fully compensate the advance of the wave; so that although there is a constant oscillation, backwards and forwards, there is a margin left for advance. Still, this advance is, after all, periodical; for, after flowing for six hours, the tide begins to ebb, and the full compensation is effected in other ​six hours. Now, the wave, breaking upon the beach, represents periodic variations; and the tide represents secular variations. Both are strictly periodical, but the latter are called secular from the comparatively vast period necessary to effect a compensation. If we conceive the ends of the oval lake to be affected only by the small waves breaking on the beach, but the sides affected by tides, we shall have an exact representation of a planetary orbit. The small waves would not sensibly lengthen or shorten the lake, but the tides would, in a marked manner. Now, the length of a planet's orbit is subject only to these very small oscillations, and it may therefore be regarded as fixed or constant. The breadth of the orbit, however, is subject to secular variations, which require ages for their full compensation. The orbit alternately bulges out into a circle, and narrows into an ellipse. The earth is now, and has been for many ages, expanding into a circle, but it will again collapse into an ellipse. The orbit may be compared to a great heart beating the pulses of eternity, alternately expanding and contracting, and each systole and diastole occupying many thousands of years. The invariable length of the orbit, or rather of the major axis, has been justly styled the Magna Charta of the planetary system, as this is the basis of its stability. The oscillations in the breadth of the ellipse are styled the secular variations of the eccentricity, the eccentricity being the amount of departure from ​a circle. The following is the great law regarding the eccentricities of the planets:—"If the mass of each planet be multiplied by the square of the eccentricity, and this product by the square of the mean distance, the sum of these quantities will always retain the same magnitude." The purport of this is, that all the disturbances of the various planets, taken together, can never exceed a certain amount, and that a small one. The planets are so related, that if one has a large share of eccentricity, another must have a small one. The case may be familiarly illustrated by supposing that a certain quantity of wine is given to be shared by several individuals, the quantity being so small, that even though it were consumed by one individual, instead of being divided equally, it would do no harm. There is, thus, only a small fund of eccentricity out of which the various planets can draw, and though one should monopolise that fund, the equilibrium of the system would not be endangered; much less can there be danger when each enjoys a share of the eccentricity. A like law has been proved in regard to the inclinations of the orbits to one another. They can never vary much from their mean position, as they draw out of a common fund, which is a small one.
The stability of the system would be destroyed by an unlimited change—first, in the dimensions of the orbit; secondly, in the form, or eccentricity; and, thirdly, in the inclination; but in all these, ​compensation is ultimately wrought out. It is easy to see how the stability would be destroyed in any one of the above ways. If the form were subject to an unlimited change in its dimensions, the circle might contract or expand, so that the planet might ultimately fall into the sun or fly off into space. The gradual change would be shewn in the length of the year, which varies with the length of the orbit, or major axis. Again, if there was no limit to the eccentricity, or if the limit was wide, the ellipse would become so narrow, and the earth would approach so near the sun, that every living thing would be destroyed. If the inclination of the orbit of the earth was not limited, as it is, it might ultimately coincide with the equator, and the distinctions of seasons would be obliterated. The conditions of life are so nicely adjusted to the present state of things, that any departure from stability, in reference to the above three points, would necessarily entail destruction upon the animal and vegetable world.
The admirable harmony and stability of the solar system, irresistibly force upon us the conviction of a superintending Intelligence. No random arrangement could secure the needful stability. We may conceive the bodies of the system arranged in innumerable ways, but only one very special arrangement would suit. We might conceive the planets moving in orbits of great eccentricity, but instead of this, they are all nearly circular. Were there no presiding ​Mind, we would expect them to move in all parts of the heavens, their orbits spanning every part of the celestial sphere, like the circles of longitude on a globe. Instead of this, we find their orbits compressed into the narrow zone of the zodiac; and the essential thing to be remarked is, that this limitation to the same plane is essential to the stability of the system. The direction in which the planets move, also exhibits the same remarkable harmony—this direction being from west to east, a condition also essential to the stability of the system. But unless we introduce the idea of design, we would have no ground to look for such a striking uniformity. Laplace has reduced to numbers the improbability of such a uniformity being a fortunate chance. By the calculus of probabilities, the chance is above four millions of times to one against the supposition that the forty-three motions (corresponding to the number of planets then known) from west to east, are the result of mere chance. He puts the probability of a primitive cause in another form, by shewing that it is two millions of times greater than the expectation that the sun will rise on the morrow. But Laplace would by no means acknowledge that this primitive cause is an Intelligent Cause, or an argument for the existence of God. His idea of a First Cause would be satisfied, if it could be shewn that the actual arrangement of the heavenly bodies necessarily resulted from the nebular hypothesis; and his opponents have, ​unfortunately, met this by virtually maintaining that, if the nebular hypothesis be true, the stability of the system must cease to be an argument for a DesigningMind. They have accordingly applied themselves to the task of disproving the hypothesis.
But granting the hypothesis proved, and that the successive abandoning of rings by the revolving mass, explained the circular character of the orbits, and the fact of their moving nearly in the same plane and in the same direction; this, so far from leading us to dispense with the necessity of a Designing Mind, would only enhance the wonder, by shewing the simplicity of the mode employed by the Divine Architect in rearing the celestial structure. It is of no consequence, as far as concerns the proof of design, whether the machine is executed mediately or immediately by the contriver. A watch may be executed by a watch-making machine, but this does not dispense with the idea of an intelligent watchmaker. Nay, the ingenuity is only increased by the ingenuity of the instrument employed. In the case of the bee, it has been attempted to explain away the intelligence involved in the construction of its cell, by shewing that its organs are so formed as to produce the requisite angles, and thus solve the problem of maxima and minima. But granting this, it is only proved that the intelligence in question works by means of tools. The employment of tools by no means lessens the ingenuity displayed in any piece of mechanism. ​And so in regard to the stability of the solar system; the nebular hypothesis, if established, would exhibit only the instrument employed by the all-wise Creator to secure the stability of the system.
In the same way we must deal with the argument founded on the arrangement by which the source of heat and light is placed in the centre of the system. Paley regards this as a proof of design solely on the ground, that there was no antecedent necessity for the sun being placed in the centre. But the force of the argument by no means rests on the disproof of an antecedent necessity—if by this is meant, some prior physical arrangement from which it resulted. According to the nebular hypothesis, the sun, as source of light and heat, must necessarily be in the centre. The sun is the incandescent mass from which the planets were thrown off, and while the planets cooled, the sun retained its high temperature. But all this only removes intelligence a step further back. The hypothesis, admitting its truth, is only the method adopted by the Divine Intelligence to secure the essential point of having the source of light and heat in the centre. Paley ascribes the difficulty of turning the mechanism of the heavens to account as an argument for a Divine Intelligence, to the circumstance, that it wants the complexity of the machines and organisms with which we are familiar on the earth. This explanation does not meet the case. There is no want of complexity in the celestial machine, though there is no ​tangible connexion between the various bodies. There is indeed no machine so complex, or one that tries the human intellect more in educing order from apparent confusion. The real difficulty lies in this, that in dealing with the solar system as a mere machine, we have not the element of life. The fundamental idea of use or design, as employed by Paley, is the adaptation of matter to the necessities of life. A thing is useful in as far as it is adapted to promote some special object in the phenomena of life. A living organism is just a system of means to ends; and every part of the system has its use. This element is wanting in the machinery of the heavens. We cannot discover a use, in this sense, in the arrangements for the stability of the system. No doubt the stability of the arrangement is essential to the welfare of the planetary inhabitants, and this may be called the use or design of the stability; but the real question is, Does the arrangement of the bodies of the solar system manifest no intelligence apart from the existence of life? A savage would, on picking up a watch, discover traces of intelligence in the structure, altogether apart from its use as a whole. He might not know how it was to benefit any being, and yet he would not fail to detect an order and a purpose. He would discover that the maintaining power and the wheels were so adjusted as to produce equable motions in the hands. He might have no conception of the use of such equable motion to any ​living being, and yet he might have no difficulty in discovering the use of the various parts of the works in producing this motion.
Let us apply this to the celestial mechanism. Suppose a spirit, wandering through space, came across our system, would he not, in pausing to contemplate its arrangements, discover proof of intelligence, though ignorant as to the existence of planetary inhabitants? Paley would hesitate to admit such a conclusion. He would maintain that you must shew the advantage of the stability of the system to living beings before you can draw a proof of intelligent design. But, as in the case of the watch, though no idea might be formed as to the use of the stability to any being, design might be clearly traced in the mode by which the stability is secured. It would be seen that planets are admirably arranged for this purpose. And the inquiring spirit would be forced, altogether apart from the idea of planetary inhabitants, to acknowledge the hand of the Divine Mechanician. Paley would insist that there would be no use in the stability if there were no beings to benefit by it, and that the planets might as well be arranged in any random order. He would be inclined to abandon the heavens as furnishing an argument per se for the existence of a Designing Mind.
All this arises from the limited range of the argument which Paley prescribed to himself. He restricted the term use to the bearing of material laws upon life. ​and was disposed to find design only when such use could be detected; and, hence, if no use in this sense could be proved for the stability of the celestial mechanism, this part of God's works could not be appealed to as proving a Designing Mind. But it looks like presumption to restrict the display of Divine Intelligence to the sphere of life. Though man had never been created, and though no living thing existed on any planet, would not the lieavens still declare the glory of God? Would not the mechanism, by which the stability of the system is secured, still manifest calculation and design? The material creation is but the projection of the Divine ideas in space and time, and it would bear the impress of the Divine Intelligence, though no finite spirit or living thing were called into being. No doubt the most marvellous display of the Divine wisdom lies in the correlation of matter to life and created intelligence. Still, while admitting the higher, we are not called to ignore the lower sphere.
We have seen that intelligence may be discovered in the adaptation of means to secure the end of stability, though we may not be able to assign any use to the stability, at least in the ordinary sense of the term. But may there not be uses other than the physical welfare of living things? Is there not a use in the very order and harmony of the solar system, apart from the more direct utilitarian purposes? Is there not an adaptation in this order and harmony to the ​training and happiness of pure intelligences? Is not a great purpose served simply by the revelation of God in nature? And even though there were no created intelligences to contemplate God's works, and lay upon his altar the tribute of adoration, would the celestial mechanism have no use? Would it not serve some purpose? Has not the material world a purpose simply in relation to the Divine Mind? The artist has a pleasure in transferring to the canvas the creations of his genius; and though no eye but his own ever beheld his pictures, they would not be without a use or purpose. Similarly we can readily conceive that the beauty and harmony of the material world serve a purpose, simply as an object of contemplation to the Divine Mind. God made all things for His own glory; and, no doubt, the highest tribute of glory is brought to Him by the play of moral and intellectual faculties, and the varied phenomena of organisation and life; but this does not hinder, that notes of praise, though feebler, should ascend to God from the play and harmony of mere physical laws. The nicely-balanced orbs of heaven speak the praises of God, as well as the harmonious exercise of the faculties of man. The heavens thus occupy an independent place in declaring the glory of God. They would declare His glory, though they served no utilitarian purpose in regard to life and organisation, and though there were no created intelligences to listen to their notes of praise.
​But the heavens declare the glory of God more emphatically, when we reflect that the stability of the whole solar system is wondrously related to the life and enjoyment of the minutest animalcule seen by the microscope, and that the heavenly hosts are a theme of devout adoration to myriads of intelligent worshippers.