Whether the universe contains within itself, under the Almighty supervision, certain arrangements and laws by which the dead world can be again cast into the crucible and regenerated by liberation through the action of heat into its primordial state once more and go the same tremendous round of planet life, we know not. The conception of such a process, even the dream or vague possibility of it, is sufficiently sublime and fills the mind with a great delight in contemplating the possible cycles through which the material universe is passing.
At any rate, we may contemplate the three great stages of world-life with which we are already acquainted--that is, the birth stage, the epoch of life and the epoch of death. There is a birth, as also a life and a death of planets. Richard A. Proctor, of great fame, on one of his last tours of instructive lecturing among our people, had for his subject the "Birth and Death of Worlds." The theme was not dissimilar to that which has been here presented in outline. The birth, the life and the death of worlds! Such is a summary of that almost infinite history through which our earth is passing--the history which the globe is _making_ on its way from its nebulous to its final state.
Such, if we mistake not, is the story epitomized--the life history in brief--of all the worlds of space. They have each in its order and kind, an epoch of the beginning, then an epoch of growth and evolution, then an epoch of life--toward which all the preceding planet history seems to tend--and finally an epoch of death which must, in the course of infinite time, swallow from sight each planet in its turn, or at least reduce each from that condition in which it is an arena of animated existence into that state where it is a frozen and desert clod, still following its wonted path through space, still shining with a cold but cheerful face, _like our moon_, upon the silent abysses of the universe.
The present century was already well advanced before there was any solid ground for the belief that the worlds of space are made of analogous or identical materials. It was only with the invention of the spectroscope and the analysis of light that the material identity of universal nature was proved by methods which could not be doubted. The proof came by the spectroscope.