not, we have here, in addition to the moon, a large array of examples, to prove how baseless is the assumption, that all the bodies of the solar system are the seats of life. 29. We have thus performed our journey from the extremest verge of the Universe, so far as we have any knowledge of it, to the orbit of our own planet; and have found, till we came into our own most immediate vicinity, strong reasons for rejecting the assumption of inhabited worlds like our own; and indeed, of the habitation of worlds in any sense. And even if Mars, in his present condition, may be some image of the Earth, in some of its remote geological periods, it is at least equally possible that he may be an image of the Earth, in the still remoter geological period before life began. Of peculiar fitnesses which make the earth suited to the sustentation of life, as we know that it is, we shall speak hereafter; and at present pass on to the other planets, Venus and Mercury. But of these, there is, in our point of view, very little to say. Venus, which, when nearest to us, fills a larger angle than any other celestial body, except the Sun and the Moon, might be expected to be the one of which we know most. Yet she is really one of the most difficult to scrutinize with our telescopes. Astronomers cannot discover in her, as in Mars, any traces of continents and seas, mountains and valleys; at least with any certainty.[12] Her illuminated part shines with an intense lustre which dazzles the sight;[13] yet she is of herself perfectly dark; and it was the discovery, that she presented the phases of the Moon, made by the telescope of Galileo, which gave the first impulse to planetary research. She is almost as large as the earth; almost as heavy. The light and heat which she receives from the Sun must be about double those which come to the earth. We discern no traces of a gaseous or watery atmosphere surrounding her. Perhaps if we could see her better, we might find that she had a surface like the moon; or perhaps, in the nearer neighborhood of the sun, she may have cooled more slowly and quietly, like a glass which is annealed in the fire; and hence, may have a smooth surface, instead of the furrowed and pimpled visage which the Moon presents to us. With this ignorance of her conditions, it is hard to say what kind of animals we could place in her, if we were disposed to people her surface; except perhaps the microscopic creatures, with siliceous coverings, which, as modern explorers assert, are almost indestructible by heat. To believe that she has a surface like the earth, and tribes of animals, like terrestrial animals, and like man, is an exercise of imagination, which not only is quite gratuitous, but contrary to all the information which the telescope gives us; and with this remark, we may dismiss the hypothesis.