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Then Lucius, smiling, thus went on: I have yet a second proportion to be added to the former, by which we will clearly demonstrate that the moon altogether resembles the earth, not only because they suffer and receive the same accidents from the same cause, but because they work the same effect on the same object. For you will without difficulty, I suppose, grant me that, of all the accidents which befall the sun, there is none so like to his setting as his eclipse, especially if you but call to mind that recent conjunction which, beginning at noonday, showed us many stars in many places of the heavens, and wrought a temperature in the air like that of the twilight. But if you will not grant me this, our friend Theon here will bring us a Mimnermus, a Cydias, an Archilochus, and besides these, a Stesichorus and a Pindar, lamenting that in eclipses the world is robbed of its brightest light, and saying that night comes on in the midst of the day, and that the rays of the sun wander in the path of darkness; but above all he will produce Homer, saying that the faces of men are in eclipses seized upon by night and darkness, and the sun is quite lost out of heaven by the conjunction of the moon. And it is natural that this should happen, When one moon’s going, and another comes. For the rest of the demonstration is, in my opinion, as certain and exactly concluding, as are the acute arguments of the mathematics. As night is the shadow of the earth, so the eclipse of the sun is the shadow of the moon, when it stands in the way of our sight. For the sun is at his setting kept from our sight by the interposition of the earth, and at his eclipse by that of the moon. Now both of these are obscurations; but that of his setting is from the earth, and that of his being eclipsed from the moon, their shadows intercepting our sight. Now the consequences of these things are easily understood. For if the effect is alike, the efficient causes are also alike; because it is of necessity that the same effects, happening in the same subjects, proceed from the same efficients. Now if the darkness in eclipses is not so profound, nor does so forcibly and entirely seize the air, as does the night, we are not to wonder at it; for the substance of the body which makes the night, and of that which causes the eclipse, is indeed the same, though their greatness is not equal. For the Egyptians, if I am not mistaken, hold that the moon is in bigness the two and seventieth part of the earth; and Anaxagoras says, she is as big as Peloponnesus. And Aristarchus shows the overthwart line or diameter of the moon to have a proportion to that of the earth which is less than if sixty were compared to nineteen, and somewhat greater than an hundred and eight compared to forty and three. Whence it happens that the earth, by reason of its greatness, wholly withdraws the sun from our sight; for it is a great obstacle and opposition, and lasts all the night. But although the moon sometimes hides all the sun, yet that eclipse continues not so long nor is so far extended, but there always appears about the circumference a certain brightness, which permits not the darkness to be black, deep, and perfectly obscure.
