It does not signify, replied the Marchioness; I can't bear the idea of these people living in perpetual darkness. You would find it still more difficult to admit the opinion, said I, if you knew that a great philosopher of ancient times had informed us that the moon was the dwelling of souls who had on earth rendered themselves worthy of very exalted happiness. He supposes that their felicity consists in listening to the music of the spheres; but that when the moon comes under the shadow of the earth, they are no longer able to hear this celestial harmony, at which time they utter the most piercing cries, and the moon hastens on as fast as possible to relieve them from this agonizing situation. We may expect then, answered she, to have the virtuous spirits sent here from the moon, for I suppose they likewise honour our world by making it an abode of the blessed: so in these two planets it is thought a sufficient reward to superior goodness for the soul to be transported from one world to the other. Really, I replied, it would not be a trifling enjoyment to take a survey of different worlds; I often receive a great deal of pleasure from such a journey, although but in imagination; what must it be then to perform it in reality? It would be much more delightful than going from here to Japan; in other words, than crawling from one end of the earth to the other with great labour, merely for the sake of seeing men. Well, said she, let us make this tour to the planets as we can; what should prevent us? We will place ourselves at all those different points of view, and at each of them survey the universe. Have we any thing else to see in the moon? You are not yet thoroughly acquainted with that world, I replied. You recollect that the two motions of the moon, by one of which she turns on her axis, and by the other round us, being equal, the latter always prevents the former from withdrawing any part from our sight, and consequently we always view the same side. That half therefore is the only part that can see our world, and as the moon, with regard to us, must be considered not to turn on her centre, the half to which we are visible, sees us always fixed in the same part of the sky.[32] When it is night, and the nights there are as long as our fortnight, she sees at first only a very small part of the earth enlightened; then a larger portion, and at length the light seems hourly to spread over the earth, till it becomes entirely luminous. On the contrary these changes in the moon are visible to us only from one night to another, because we are a long time without seeing her. I should like to hear the mistakes which the philosophers of that world fall into from the apparent immobility of our earth, whilst all the other heavenly bodies rise and set in the space of a fortnight. Probably they consider the earth immovable in consequence of her enormous size, being sixty times larger than the moon; and when