Swift, in Gulliver’s Travels, conceived of a land where the intelligence and conscience of Man dwelt in the form of the horse, and the human form tabernacled the instincts of the beast. H. G. Wells, in his War of the Worlds, attributed intelligence to monsters—half-cuttlefish and half-anemone,—and the human form to their helpless, unresisting prey. Both conceptions are as scientifically absurd as they are gross and revolting; and if it were possible for the skeleton of creatures from other worlds to be brought to us here, then biologists would as confidently pronounce on their intelligence as they do on the extinct forms of bygone ages—the nearer to the human form, the nearer to the human mind. We have found the figures of reindeer, horse, and mammoth scratched in outline on a mammoth tusk; but though the artist has left no other trace, we need no further evidence of his bodily form. Neither horse, nor reindeer, nor mammoth made those rough outlines; they were drawn by a man. More striking still, France yields us chipped flints by the million, flints so slightly shaped that it is in dispute whether they may not have been so broken by the action of torrents. But there are only two theories about them; either they were so chipped by natural action, or they were designedly so chipped by creatures resembling ourselves in head and hand.
The question that has been dealt with in this volume is a scientific one, and the attempt has been made to treat it as such, and to argue from known physical facts as to the conditions of worlds which we cannot visit. But by many the question is generally discussed wholly apart from physical facts at all, and it becomes one of sentiment and of religious sympathy. Yet, curiously enough, the division between those who think that all worlds must be inhabited and those who think that our own world stands alone is not coincident with any line of theological divisions, but rather cuts across all such. Some believers in Christianity argue that since God has filled this world with Life, Life has been His purpose in the world, and must therefore have been His purpose in all other worlds—they too must be filled with Life in like manner. Other believers argue that this world was the scene of the Incarnation of Our Lord, and is therefore unique in that respect; and that this uniqueness sets its stamp upon this world in all respects. Opponents to Christianity are divided into the same two classes, the one arguing that wherever there is matter the inevitable course of evolution will produce life, and eventually intelligent life. The other class are equally clear that all forms of life are special, the result of the particular environment, and that it is unreasonable to expect that any other world has had the same history as our own, or that the same special conditions have prevailed elsewhere. In other words the belief that there are other inhabited worlds has depended chiefly neither on science nor on religious belief, but upon sentiment. There are some who like to think themselves, and the race to which they belong, altogether exceptional; others delight in finding themselves reflected wherever they look. So far as Science has progressed and can return an answer to an enquiry that exceeds so far the bounds of our direct observation, it dissents from both orders of thought. The conditions of life are indeed narrow, special, restricted; intelligent, organic life must, relatively speaking, be a rarity in the universe, but we lack the information that would enable us to affirm with any confidence that such life is only to be found upon this world of ours. Heavy as the odds are against any particular world being an inhabited one, yet when the limitless extent of space is considered, and the innumerable numbers of stars and systems of stars, it seems but reasonable to conclude that though inhabited worlds are relatively rare, the absolute number of them may be considerable; considerable, if not at one particular moment of time, yet when the whole duration of the universe is admitted.
But there is a religious question connected with this enquiry; one that goes down to the very roots of man’s deepest thoughts and aspirations. As individuals our days on the Earth are as a shadow, and there is none abiding; as individuals we pass and disappear; and though the race remains, yet as far as science can guide us and enable us to penetrate the future, the same lot awaits the race as well. Slowly but surely the water of a planet will combine with its substance or disappear into its crust. The cooling of the Sun, though it may be long delayed, would seem to be inevitable in the sequel.
“Oh, life as futile then as frail.
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What hope of answer or redress?
Behind the veil, behind the veil.”
It is to this veil that we are now brought. It seems impossible to believe that Life, so rare a fruit of the universe, intelligent Life, conscious Life, to which the long course of evolution has been so manifestly leading up all through the long ages, should have no better destiny than a final and hopeless extinction; that this Earth and all the efforts and aspirations of the long generations of men should have no worthier end than to swing, throughout the eternal ages, an empty, frozen heap of dust, circling round the extinct cinder that was once its Sun. If we look backward, we seem to discern clear signs of progress; if we look forward, we discern nothing but the veil. Science is but organized experience, and experience of the future we have none.
There was a time when on this world there was no life; a time when life began. How did it begin? Under what conditions?
Of that great change—when non-living matter first became endowed with life, became so endowed not by the action and intervention of other living matter, but without it—we have no knowledge, no experience. And so long as this continues to be the case, that change, the greatest physical change that has yet taken place in the history of the universe, the first change of the non-living into the living, is outside the reach of science; it lies beyond its border. We may guess and speculate about it, but speculation is not science; we may spin words about it with the utmost skill of the dialectician, but metaphysics is not science; it can never come within the scope of science until it has first come within the scope of experience.
There is, therefore, a veil behind us as well as the one that encloses us in front; and as hitherto Science has failed to pierce the veil of the past, it is even less able to pierce the veil of the future; for of the future we have no experience.
Here, then, our enquiry must end, for it is an enquiry of physical science; the search for living material organisms endowed with intelligence. How life first came upon this Earth, or when, or where, is beyond the power of science to determine. Yet it did come. There was a time when there was no life here; none, not even the humblest form of it; nor was there any hint or foreshadowing of it, still less of all its infinities of form, and possibilities of development.