17. The belief that other planets, as well as our own, are the seats of habitation of living things, has been entertained, in general, not in consequence of physical reasons, but in spite of physical reasons; and because there were conceived to be other reasons, of another kind, theological or philosophical, for such a belief. It was held that Venus, or that Saturn, was inhabited, not because any one could devise, with any degree of probability, any organized structure which would be suitable to animal existence on the surfaces of those planets; but because it was conceived that the greatness or goodness of the Creator, or His wisdom, or some other of His attributes, would be manifestly imperfect, if these planets were not tenanted by living creatures. The evidences of design, of which we can trace so many, and such striking examples, in our own sphere, the sphere of life, must, it was assumed, exist, in the like form, in every other part of the universe. The disposition to regard the Universe in this point of view, is very general; the disinclination to accept any change in our belief which seems, for a time, to interfere with this view, is very strong; and the attempt to establish the necessity of new views discrepant from these has, in many eyes, an appearance as if it were unfriendly to the best established doctrines of Natural Theology. All these apprehensions will, we trust, be shown, in the sequel, to be utterly unfounded: and in order that any such repugnance to the doctrines here urged, may not linger in the reader's mind, we shall next proceed to contemplate the phenomena of the universe in their bearing upon such speculations. FOOTNOTES: [1] Other speculators also have regarded Saturn's Ring as a ring of cloud or water. See _Cosmos_, III. 527 and 553. [2] Humboldt has already remarked _(Cosmos_, I. 95, and III. 427), that the inner planets as far as Mars, and the outer ones beginning with Jupiter, form two groups having different properties. Also Encke. (See Humboldt's Note.) [3] Printed Oct. 19, 1853. [4] Herschel, 540. [5] It is probable, from the small density of Jupiter's satellites, that they also consist in a great measure of water and vapor. Only one of them is denser than Jupiter himself.--_Cosmos_. [6] It has, in our own day, even in the present year, been regarded as a great achievement of man to direct the fiery influences which he can command, so as to cast a colossal statue in a single piece, instead of casting it in several portions. [7] Herschel, 900-905. [8] Herschel, 901. [9] Besides the curious relation of the times of rotation of the planets, just noticed, there is another curious relation, of their distance from the Sun, which any one, wishing to frame an hypothesis on the origin of our Solar System, ought by all means to try to account for. The distances from the Sun, of the planets, Mercury, Venus, Earth, Mars, the Planetoids, Jupiter, Saturn, Uranus, are nearly as the numbers,