In the fifth place, the changing state of the world has been regarded as incompatible with the world's eternity. This argument is thus stated by Bishop Sumner: "If the universe itself is the first eternal being, its existence is necessary, as metaphysicians speak; and it must be possessed of all those qualities which are inseparable from necessary existence. Of this nature are immutability and perfection. For change is the attribute of imperfection, and imperfection is incompatible with that Being, which is, as the hypothesis affirms, independent, and, therefore, can have no source of imperfection. To suppose, therefore, of the first independent Being, that it could have existed otherwise than it is, is no less contrary to the idea of necessity, with which we set out, than to suppose it not to exist at all."
This reasoning is not destitute of plausibility. For there is scarcely any lesson more forcibly impressed on short-lived man than the mutability of the world. And it is indeed true that change is its most striking attribute. But when we look at the subject philosophically, we find that all this mutability is consistent with the most perfect ultimate stability; nay, that the change is essential to secure the stability. Apart from what revelation and geology teach, these changes in nature form cycles, which, like those in astronomy, are perfectly consistent with the eternal permanence of the general system to which they belong. In the motions of the heavenly bodies, a considerable amount of irregularity and oscillation about a mean state does not tend to the ruin, but rather to the preservation, of the system, provided the anomalies do not extend beyond certain limits. It is just so with other changes that are going on around us. All of them are, in fact, as much regulated by mathematical laws as the perturbations of the heavenly bodies; although those laws are more complicated and difficult to bring out in distinct formulæ in the former case than in the latter. Yet even in astronomy, it is not many years since the mutual disturbances among the heavenly bodies were supposed to be the certain precursors of ruin to the system. It was not till the famous problem of the three bodies was solved, by the use of the most refined mathematical analysis, that astronomers learnt the true operation of those causes of disturbance among the heavenly bodies which exist in their mutual attractions. It was then found that, so balanced are they in their action, and so narrow their limits, that they can never affect the stability of the system; or, rather, they secure that stability. It is, indeed, true, that when changes in nature go on increasing or decreasing in magnitude indefinitely, they clearly indicate a beginning and an end to the system to which they belong. And it was on this principle that the earlier astronomers predicted that the celestial perturbations would ultimately bring the universe to a state of chaos. They found, for instance, that the moon's orbit was decreasing in size, and they inferred that, ultimately, that luminary must come to the earth. But they now know it to be mathematically certain that, after a long period, the diminution of the orbit will cease; it will begin to expand, and go on expanding,-until the opposite point of oscillation is reached, when it will again diminish; and in this manner, if God's will permit, perform its eternal round. Just so it is with all the irregularities of the solar system.