It is quite different when we lift up our eyes to examine the face of heaven. We have no grasp whatever of the incommensurable spiraloids of innumerable worlds to which our own belongs; we have no means of communicating with the inhabitants of other planets; we cannot establish any interchange of thought with the _men_ (if there be any) of Mercury, Venus, Mars, Jupiter, Saturn,--who form, perhaps, like the _men_ of the earth, the most elevated circle of material life, varying under an infinity of forms upon each of their floating domiciles.... I see you smiling, reader, because you do not believe that these _other earths_--satellites of the sun, like our own--are inhabited by beings analagous to our human race. You are at liberty not to believe it. But then, to be in agreement with yourselves, you ought to declare in favour of the Science of the Past, though demonstrated to be false, against the Science of the Present. Will you do so? Certainly not. But then, of two things, one: either you will be obliged to make the earth an unique exception, a kind of monstrosity in the midst of the other mechanism of the universe, which will be to throw yourself back upon the erroneous science of the ancients; or you must perforce admit that the earth is not specially privileged, and that the other planets, its companions, have also their human inhabitants. * * * * * Is this all? Alas, all this is nothing! The other worlds whose suns appear to us under the form of scintillating points or stars, will, undoubtedly, in like manner, possess their systems of planets and satellites. Why should they divaricate from the general plan of the universe? Now, multiply the number of the stars--who has counted them?--with the probable number of their planets, and you will gain, if this be permitted you, the number of _humanities_ who people yonder star-sown space. And it is not only with _these_ we must be able to correspond, but with the humanities of all the nebulæ of all the firmaments--for remember our starry heaven itself is but a nebula--that we must establish an interchange of ideas, if you would have your power, and civilisation, and intellectual royalty, something more than a mere optical illusion of your pride. * * * * *