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offer further comment on this passage, the tendency of which, when rightly understood, is manifestly so far from hostile to the true doctrine of final causes, that it points directly to those profoundly adjusted arrangements which constitute the very soundest proofs of Divine Intelligence pervading the system of the universe.
Perturbations:-Stability of the System.
NEWTON developed in the most complete and satisfactory manner all the grander features of the system of universal gravitation. To that great principle, simple indeed in its law, but wholly mysterious in its nature and mode of operation, he successfully referred all the more palpable and conspicuous motions of the heavenly bodies. Here was, in truth, a physical cause of the most universal efficiency, but one which he was peculiarly careful to insist on, in the sole sense of an universal fact or law;-the tendency of all matter to fall together with a force proportional directly to the mass and inversely to the square of the distance. To this physical cause, then, he was able to trace all the greater phenomena of the solar system.
But it was confessedly the fact that there existed some slight irregularities in the motions of the planets; and it was even a consequence of gravitation that they must act one on another, in a very complicated manner, in consequence of their perpe
tually varying relative positions, and thus disturb the perfect regularity of each other's motion. The investigation of those perturbations was not followed up by Newton. He was aware of their existence, and that they were but small in amount, and always allowed for them in speaking of the exactness with which the law of elliptic orbits prevails. He conceived, however, that these "inconsiderable irregularities which may have arisen from the mutual actions of comets and planets upon one another, will be apt to increase, till this system wants a reformation *."
This remark occurs in a passage where he is expressly speaking of the order and harmony of the system as an indication of design. He had also before said; that "the main business of natural philosophy is to deduce causes from effects till we come to the very first cause, which certainly is not mechanicalt." And again, that from observing the order of the visible world, and so inferring creative intelligence, "it is unphilosophical to seek for any other origin of the world, or to pretend that it might arise out of a chaos by the mere laws of nature; though being once formed it may continue by those laws for many ages."
The observation first quoted has, in conjunction with these last, been viewed as expressing Newton's belief that the adjustments of the planetary system
Opticks, Query 31, p. 378, 3d edit. p. 344.
would need renewal from time to time by the immediate interposition of Divine power. And this was looked upon by many as one of the most valuable inferences from the Newtonian system. From a reference to the passage, it will be seen at once that Newton does not himself expressly make the inference; nor, when carefully considered, is it one of any peculiar importance or force. It is difficult to see in what way (if correct,) it could add to the evidence of design afforded in such overwhelming abundance by the existing order of the system.
Newton left all the irregularities, or perturbations (as they are called,) to be investigated by his successors. The most distinguished mathematicians since his time have been occupied in developing and simplifying these intricate but highly interesting questions. Lagrange and Laplace have been pre-eminently distinguished in this research; and to the profound analysis, especially, of the latter, we owe the establishment of the great principle, that all the variations which can arise from the mutual actions of the planets are limited by certain periods within which they must perpetually recur. This has been called "the stability of the planetary system."
"It is not, therefore," says Baron Fourier, in his Eloge of Laplace, "left, as Newton himself and Euler had conjectured, to an adventitious force to repair or prevent the disturbances which time may have caused. It is the law of gravitation itself which regulates all things, which is sufficient for all things,
and which everywhere maintains variety and order. Having once emanated from Supreme Wisdom, it presides from the beginning of time, and renders impossible every kind of disorder. Newton and Euler were not acquainted with all the perfection of the universe."
Or, in the words of Laplace himself, "It seems that nature has ordered every thing in the heavens to ensure the duration of the planetary system by views similar to those which she appears to us so admirably to follow upon the earth for the preservation of animals and the perpetuity of species*."
This great discovery has become matter of unmeasured censure to those who were intent upon finding an immediate agency of the Deity in every event; and who were unable to see, that so far from detracting from the evidences of Supreme Intelligence, this recondite provision for the perpetual maintenance, of the order of the universe is, of all others, the most stupendous manifestation of eternal Providence.
Attaching importance, as we before observed, to the supposed necessity for Divine interference, to preserve the regularity of the system, they were of course proportionally offended at the announcement of the principle of physical stability. They were blind to the infinitely higher views thus disclosed.
They have applauded Newton for pointing to an ultimate cause" which is not mechanical," but they * Systéme du Monde, 442.
have been little able to perceive the nature or indications of such a cause. They have looked for the proofs of Omnipotence rather in great changes and sudden interpositions, but have not acknowledged infinite Intelligence in the continual invariable succession of ordinary laws, and the profound adjustment of all the varied trains of physical effects one to another, the preservation of uninterrupted and universal harmony among natural phenomena.
BUT though we find the principle of gravitation thus perfect within itself, and containing a perpetual source of reparation for all disturbances, yet here we must not restrict our speculations to the action of gravitation alone; no part of the universe, no physical principle must be contemplated in an isolated point of view. The consequences of gravitation must not be regarded alone without also considering other causes by which they may be modified; and the disclosure of the high probability that the planetary spaces are filled by a medium inconceivably rare, yet capable, in an immense lapse of time, of sensibly resisting the motions of the planets, opens to our view an extraneous cause which will modify the effects resulting from the action of gravitation alone. The perturbations may be perpetually compensated; but the orbits of all the bodies of the system will, by the resistance of the æthereal