5. But is such an assumption true? Is such a principle well founded? The best chance which we have of learning whether it is so, is to endeavor to ascertain the fact, in the body which is nearest to us; and thus, the best placed for our closer scrutiny. This is, of course, the Moon; and with regard to the Moon, we have, again, this advantage in beginning the inquiry with her:--that she, at least, is in circumstances, as to light and heat, so far as the Sun's distance affects them, which we know to be quite consistent with animal and vegetable life. For her distance from the Sun is not appreciably different from that of the Earth; her revolutions round the earth do not make nearly so great a difference, in her distance from the sun, as does the earth's different distances from the sun in summer and in winter: the fact also being, that the earth is considerably nearer to the sun in the winter of this our northern hemisphere, than in the summer. The moon's distance from the sun then, adapts her for habitation: is she inhabited? 6. The answer to this question, so far as we can answer it, may involve something more than those mere astronomical conditions, her distance from the sun, and the nature of her motions. But still, if we are compelled to answer it in the negative;--if it appear, by strong evidence, that the Moon is not inhabited; then is there an end of the general principle, that, _all_ the bodies of the solar system are inhabited, and that we must begin our speculations about each, with this assumption. If the Moon be not inhabited, then, it would seem, the belief that each special body in the system is inhabited, must depend upon reasons specially belonging to that body; and cannot be taken for granted without such reasons. Of the two bodies of the solar system which alone we can examine closely, so as to know anything about them, the Earth and the Moon, if the one be inhabited, and the other blank of inhabitants, we have no right to assume at once, that any other body in the solar system belongs to the former of these classes rather than to the latter. If, even under terrestrial conditions of light and heat, we have a total absence of the phenomenon of life, known to us only as a terrestrial phenomenon; we are surely not entitled to assume that when these conditions fail, we have still the phenomenon, life. We are not entitled to _assume_ it; however it may be capable of being afterwards proved, in any special case, by special reasons; a question afterwards to be discussed.