star must mingle in a distant view with their central sun; for instance, when you see our Sun from afar with the planets of his system, is it possible for you to distinguish our Earth amongst them?

LUMEN. You have raised the single geometrical objection which seems to contradict all previous experience. In point of fact, at a certain distance the planets are absorbed in their suns, and our terrestrial eyes would have difficulty in distinguishing them. You know that from Saturn the Earth is invisible. But you must remember that this discrepancy arises as much from the imperfection of our sight as from the geometrical law of the decrease of surfaces. Now, in the world on which I had just landed, the inhabitants are not incarnated in a gross form, as we are here below, but are free beings, and endowed with eminently powerful faculties of perception. They can, as I have told you, _isolate_ the source of light from the object lighted, and, moreover, they can perceive distinctly details which at that distance would be absolutely hidden from the eyes of those dwelling upon this Earth.QUÆRENS. Do they make use, then, of instruments superior to our telescopes?
LUMEN. Well, if, in order to realise this marvellous faculty, you find
it easier to suppose that they possess such instruments, you may do so, in theory. Imagine a telescope which, by a succession of lenses and an arrangement of diaphragms, brings near in succession these distant worlds, and isolates each one in the field of view in order to study it separately. I should also inform you that these beings are endowed with a special sense by which they can regulate at will the powers of their marvellous organs of sight. And you must further understand that this power and this regulation of vision are natural in those worlds, and not supernatural. In order to conceive of the faculties possessed by these ultra-terrestrial beings, reflect for a moment upon the eyes of some insects--of those, for instance, which have the power to draw in, to lengthen out, or to flatten the crystalline lens so as to make it magnify in different degrees; or of those which can concentrate on the field of view a multitude of eyes in order to bring them to bear upon the desired object.

QUÆRENS. Yes, I can imagine it to be possible. Then you are able to see the Earth, and to distinguish from above even the towns and villages of our lower world?
LUMEN. Let me proceed with my description. I found myself then upon the ring-shaped world, the size of which I told you is great enough to make two hundred worlds like yours. The mountain on which I stood was covered with trees woven into arboreal palaces. These fairy-like chateaux seemed to 

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