'Tis precisely the same thing, I replied; we take upon us to decide on every thing, but we are never in a proper place for making our observations. We would form an opinion of ourselves, and we are too near; we would judge of others; they are too distant from our view. We should be placed between the earth and the moon to form a just comparison; a spectator, not an inhabitant of the world. I shall be inconsolable for the injustice we do our world, said she, and the partial regard we have for the moon, unless you can assure me that the inhabitants of that planet are as ignorant of _their_ advantages, and consider our globe a luminous body, without knowing that from their own we derive so much light. I can make you easy on that head, answered I; we are certainly a luminary to them: they do not, it is true, see us describe a circle round them,[19] but that does not signify. The reason of our appearing to remain in the same place is this;--the side of the moon which was turned towards us at the creation, has always continued so; we always observe the same eyes, mouth, and other features of the face which, by the help of imagination, we have contrived out of the spots on her surface.[20] If the other half were presented to us, we should see spots arranged in a different form: this does not arise from the moon's not turning on her axis; she turns in the same time that is employed in going round the earth, that is, a month; but whilst she is performing part of her revolution on her axis, she at the same time performs an equal part of her circle round the earth, and thus, by putting herself in a new situation, continues to shew the same side: therefore although with regard to the sun and the rest of the heavenly bodies the moon evidently turns on her axis, yet when viewed from the earth she does not appear to do so. All the other luminaries seem to the moon to rise and set in the space of a fortnight, but she constantly sees our globe in the same part of the heavens.[21] This apparent immobility, were it invariable, would be thought inconsistent with the nature of a planet; but the moon has a sort of vibratory motion which sometimes conceals a small part of the face, and exhibits a part of the other side. Now, I can venture to say that the inhabitants attribute this motion to us, and imagine that we vibrate in the heavens, like a pendulum. [Footnote 19: This is an error, for if they consider the earth's situation relatively to the firmament, they must see that she performs a revolution in twenty-seven days: they certainly always find her answer to their zenith, or at the same distance from the zenith, but at the same time this zenith is continually answering to some new point in the heavens.]