32. But even if we could assent to the opinion, as probable, that there may occur, on some other planet, progressions of organized forms analogous in some way to that series of animal forms which has appeared upon the earth, we should still have no ground to assume that this series must terminate in a rational and intelligent creature like man. For the introduction of reason and intelligence upon the Earth is no part nor consequence of the series of animal forms. It is a fact of an entirely new kind. The transition from brute to man does not come within the analogy of the transition from brute to brute. The thread of analogy, even if it could lead us so far, would break here. We may conceive analogues to other animals, but we could have no analogue to man, except man. Man is not merely a higher kind of animal; he is a creature of a superior order, participating in the attributes of a higher nature; as we have already said, and as we hope hereafter further to show. Even, therefore, if we were to assume the general analogy of the Stars and of the Sun, and were to join to that the information which geology gives us of the history of our own planet; though we might, on this precarious path, be led to think of other planets as peopled with unimagined monsters; we should still find a chasm in our reasoning, if we tried, in this way, to find intelligent and rational creatures in planets which may revolve round Sirius or Arcturus. 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