of other planets, as well as to man. The existence of our own minds directs us, as I have said, to a Supreme Mind; and the nature of Mind is conceived to be, in all its manifestations, so much the same, that we can conceive minds to be multiplied indefinitely, without fear of confusion, interference, or exhaustion. There may be, in Jupiter, creatures endowed with an intellect which enables them to discover and demonstrate the relations of space; and if so, they cannot have discovered and demonstrated anything of that kind as true, which is not true for us also: their Geometry must coincide with ours, as far as each goes:—thus showing how absurdly, as Plato long ago observed, we give to the science which deals with the relations of space, a name (geometry), borrowed from the art of measuring the earth. The earth with its properties is no more the special basis of geometry, than are Jupiter or Saturn, or, so far as we can judge, Sirius or Arcturus and their systems, with their properties. Wherever pure intellect is, we are compelled to conceive that, when employed upon the same objects, its results and conclusions are the same. If there be intelligent inhabitants of the Moon, they may, like us, have employed their intelligence in reasoning upon the properties of lines and angles and triangles; and must, so far as they have gone, have arrived, in their thoughts, at the same properties of lines and angles and triangles, at which we have arrived. They must, like us, have had to distinguish between right angles and oblique angles. They may have come to know, as some of the inhabitants of the earth came to know, four thousand years ago, that, in a right-angled triangle, the square on the larger side is equal to the sum of the squares on the other two sides. We can conceive occurrences which would give us evidence that the Moon, as well as the Earth, contains geometers. If we were to see, on the face of the full moon, a figure gradually becoming visible, representing a right-angled triangle with a square constructed on each of its three sides as a base; we should regard it as the work of intelligent creatures there, who might be thus making a signal to the inhabitants of the earth, that they possessed such knowledge, and were desirous of making known to their nearest neighbors in the solar system, their existence and their speculations. In such an event, curious and striking as it would be, we should see nothing but what we could understand and accept, without unsettling our belief in the Supreme and Divine Intelligence. On the contrary, we could hardly fail to receive such a manifestation as a fresh evidence that the Divine Mind had imparted to the inhabitants of the Moon, as he has to us, a power of apprehending, in a very general and abstract form, the relations of that space in which he performs his works. We should judge, that having been led so far in their speculations, they must, in all probability, have been led also to a conception of the Universe, as the field of action of a universal and Divine Mind; that having thus become geometers, they must have ascended to the Idea of a God who works by geometry.
4. But yet, by such a supposition, on further consideration, we find ourselves introduced to views entirely different from those to which we are led by the supposition of mere animal life, existing in other worlds than the earth. For, not to dwell here upon any speculations as to how far the operations of our minds may resemble the operations of the Divine Mind;—a subject which we shall hereafter endeavor to discuss;—we know that the advance to such truths as those of geometry has been, among the inhabitants of the earth, gradual and progressive. Though the human mind have had the same powers and faculties, from the beginning of the existence of the race up to the present time, (as we cannot but suppose,) the results of the exercise of these powers and faculties have been very different in different ages; and have gradually grown up, from small beginnings, to the vast and complex body of knowledge concerning the scheme and relations of the Universe, which is at present accessible to the minds of human speculators. It is, as we have said, probably about four thousand years, since the first steps in such knowledge were made. Geometry is said to have had its origin in Egypt; but it assumed its abstract and speculative character first among the Greeks. Pythagoras is related to have been the first who saw, in the clear light of demonstration, the property of the right-angled triangle, of which we have spoken. The Greeks, from the time of Socrates, stimulated especially by Plato, pursued, with wonderful success, the investigation of this kind of truths. They saw that such truths had their application in the heavens, far more extensively than on the earth. They were enabled, by such speculations, to unravel, in a great degree, the scheme of the universe, before so seemingly entangled and perplexed. They determined, to a very considerable extent, the relative motions of the planets and of the stars. And in modern times, after a long interval, in which such knowledge was nearly stationary, the progress again began; and further advances were successively made in man's knowledge of the scheme and structure of the visible heavens; till at length the intellect of man was led to those views of the extent of the Universe and the nature of the stars, which are the basis of the discussions in which we are now engaged. And thus man, having probably been, in the earliest ages of the existence of the species, entirely ignorant of abstract truth, and of the relations which, by the knowledge of such truth, we can trace in nature, (as the barbarous tribes which occupy the greater part of the earth's surface still are;) has, by a long series of progressive steps, come into the possession of knowledge, which we cannot regard without wonder and admiration; and which seems to elevate him in no inconsiderable degree, towards a community of thought with that Divine Mind, into the nature and scheme of whose works he is thus permitted to penetrate.
5. Now the knowledge which man is capable, by the nature of his mental faculties, of acquiring, being thus blank and rudimentary at first, and only proceeding gradually, by the steps of a progress, numerous, slow, and often long interrupted, to that stage in which it is the basis of our present speculations; the view which we have just taken, of the nature of Intellect, as a faculty always of the same kind, always uniform in its operations, always consistent in its results, appears to require reconsideration; and especially with reference to the application which we made of that view, to the intelligent inhabitants of other planets and other worlds, if such inhabitants there be. For if we suppose that there are, in the Moon, or in Jupiter, creatures possessing intellectual faculties of the same kind as those of man; capable of apprehending the same abstract and general truths; able, like man, to attain to a knowledge of the scheme of the Universe; yet this supposition merely gives the capacity and the ability; and does not include any security, or even high probability, as it would seem, of the exercise of such capacity, or of the successful application of such ability. Even if the surface of the Moon be inhabited by creatures as intelligent as men, why must we suppose that they know anything more of the geometry and astronomy, than the great bulk of the less cultured inhabitants of the earth, who occupy, really, a space far larger than the surface of the Moon; and, all intelligent though they be, and in the full possession of mental faculties, are yet, on the subjects of geometry and astronomy, entirely ignorant;—their minds, as to such a knowledge, a blank? It does not follow, then, that even if there be such inhabitants in the Moon, or in the Planets, they have any sympathy with us, or any community of knowledge on the subjects of which we are now speaking. The surface of the Moon, or of Jupiter, or of Saturn, even if well peopled, may be peopled only with tribes as barbarous and ignorant as Tartars, or Esquimaux, or Australians; and therefore, by making such a supposition, we do little, even hypothetically, to extend the dominion of that intelligence, by means of which all intelligent beings have some community of thought with each other, and some suggestion of the working of the Divine and Universal Mind.
6. But, in fact, the view which we have given of the mode of existence of the human species upon the earth, as being a progressive existence, even in the development of the intellectual powers and their results, necessarily fastens down our thoughts and our speculations to the earth, and makes us feel how visionary and gratuitous it is to assume any similar kind of existence in any region occupied by other beings than man. As we have said, we have no insuperable difficulty in conceiving other parts of the Universe to be tenanted by animals. Animal life implies no progress in the species. Such as they are in one century, such are they in another. The conditions of their sustentation and generation being given, which no difference of physical circumstances can render incredible, the race may, so far as we can see, go on forever. But a race which makes a progress in the development of its faculties cannot thus, or at least cannot with the same ease, be conceived as existing through all time, and under all circumstances. Progress implies, or at least suggests, a beginning and an end. If the mere existence of a race imply a sustaining and preserving power in the Creator, the progress of a race implies a guiding and impelling power; a Governor and Director, as well as a Creator and Preserver. And progress, not