33. The reasonable view of the matter appears to be this. The assumption that the Fixed Stars are of exactly the same nature as the Sun, was, at the first, when their vast distance and probable great size were newly ascertained, a bold guess; to be confirmed or refuted by subsequent observations and discoveries. Any appearances, tending in any degree to confirm this guess, would have deserved the most considerate attention. But there has not been a vestige of any such confirmatory fact. No planet, nor anything which can fairly be regarded as indicating the existence of a planet, revolving about a star, has anywhere been discerned. The discovery of nebulæ, of binary systems, of clusters of stars, of periodical stars, of varying and accelerated periods of such stars, all seem to point the other way. And if all these facts be held to be but small in amount, as to the information which they convey, about the larger, and perhaps nearer stars; still they leave the original assumption a mere guess, unsupported by all that three centuries of most diligent, and in other respects successful research, has been able to bring to light. That Copernicus, that Galileo, that Kepler, should believe the stars to be Suns, in every sense of the term, was a natural result of the expansion of thought which their great discoveries produced, in them and in their contemporaries. Nor are we yet called upon to withdraw from them our sympathy; or entitled to contradict their conjecture. But all the knowledge that the succeeding times have given us; the extreme tenuity of much of the luminous matter in the skies; the existence of gyratory motion among the stars, quite different from planetary systems; the absence of any observed motions at all resembling such systems; the appearance of changes in stars, quite inconsistent with such permanent systems; the disclosure of the history of our own planet, as one in which changes have constantly been going on; the certainty that by far the greater part of the duration of its existence, it has been tenanted by creatures entirely different from those which give an interest, and thence, a persuasiveness, to the belief of inhabitants in worlds appended to each star; the impossibility, which appears, on the gravest consideration, of transferring to other worlds such interests as belong to our own race in this world; all these considerations should, it would seem, have prevented that old and arbitrary conjecture from growing up, among a generation professing philosophical caution, and scientific discipline, into a settled belief.
34. Some of the moral and theological views which tend to encourage and uphold this belief, may be taken under our more special consideration hereafter: but here, where we are reasoning principally upon astronomical grounds, we may conclude what we have to remark about the Fixed Stars, as the centres of inhabited systems of worlds, by saying; that it will be time enough to speculate about the inhabitants of the planets which belong to such systems, when we have ascertained that there are such planets, or one such planet. When that is done, we can then apply to them any reasons which may exist, for believing that all, or many planets, are the seats of habitation of living things. What reasons of this kind can be adduced, and what is their force with regard to our own solar system, we must now proceed to discuss.[23]
FOOTNOTES:
[1] Herschel, 866.
[2] Ibid. 866.
[3] Herschel, 846.
[4] Herschel, 848.
[5] That these systems have not condensed to one centre, appears to imply a less complete degree of condensation than exists in those systems which have done so.
[6] Herschel, 850.
[7] Herschel, 847.