3At the same time one day the sky in the east was perceived to be covered with a thick darkness, and from daybreak to noon the stars were visible throughout; and, as an addition to these terrors, while the light of heaven was thus withdrawn, and the world almost buried in clouds, men, from the length of the eclipse, began to believe that the sun had wholly disappeared. Presently, however, it was seen again like a new moon, then like a half-moon, and at last it was restored entire.
2A thing which on other occasions did not happen so visibly except when after several unequal revolutions, the moon returns to exactly the same point at fixed intervals; that is to say, when the moon is found in the same sign of the zodiac, exactly opposite to the rays of the sun, and stops there a few minutes, which in geometry are called parts of parts.
3And although the changes and motions of both sun and moon, as the inquiries into intelligible causes have remarked, perpetually return to the same conjunction at the end of each lunar month, still the sun is not always eclipsed on these occasions, but only when the moon, as by a kind of balance, is in the exact centre between the sun and our sight.
4In short, the sun is eclipsed, and his brilliancy removed from our sight, when he and the moon, which of all the constellations of heaven is the lowest, proceeding with equal pace in their orbits, are placed in conjunction in spite of the height which separates them (as Ptolemy learnedly explains it), and afterwards return to the dimensions which are called ascending or descending points of the ecliptic conjunctions: or, as the Greeks call them, defective conjunctions. And if these great lights find themselves in the neighbourhood of these points or knots, the eclipse is small.
5But if they are exactly in the knots which form the points of intersection between the ascending and descending path of the moon, then the sky will be covered with denser darkness, and the whole atmosphere becomes so thick that we cannot see what is close to us.
6Again, the sun is conceived to appear double when a cloud is raised higher than usual, which from its proximity to the eternal fires, shines in such a manner that it forms the brightness of a second orb as from a purer mirror.
7Now let us come to the moon. The moon sustains a clear and visible eclipse when, being at the full, and exactly opposite to the sun, she is distant from his orb one hundred and eighty degrees, that is, is in the seventh sign; and although this happens at every full moon, still there is not always one eclipse.
8But since she is always nearest to the earth as it revolves, and the most distant from the rest of the other stars, and sometimes exposes itself to the light which strikes it, and sometimes also is partially obscured by the intervention of the shade of night, which comes over it in the form of a cone; and then she is involved in thick darkness, when the sun, being surrounded by the centre of the lowest sphere, cannot illuminate her with his rays, because the mass of the earth is in the way; for opinions agree that the moon has no light of her own.
9And when she returns to the same sign of the zodiac which the sun occupies, she is obscured (as has been said), her brightness being wholly dimmed, and this is called a conjunction of the moon.
10Again the moon is said to be new when she has the sun above her with a slight variation from the perpendicular, and then she appears very thin to mankind, even when leaving the sun she reaches the second sign. Then, when she has advanced further, and shines brilliantly with a sort of horned figure, she is said to be crescent shaped; but when she begins to be a long way distant from the sun, and reaches the fourth sign, she gets a greater light, the sun’s rays being turned upon her, and then she is of the shape of a semicircle.
11As she goes on still further, and reaches the fifth sign, she assumes a convex shape, a sort of hump appearing from each side. And when she is exactly opposite the sun, she shines with a full light, having arrived at the seventh sign; and even while she is there, having advanced but a very little further, she begins to diminish, which we call waning; and as she gets older, she resumes the same shapes that she had while increasing. But it is established by unanimous consent that she is never seen to be eclipsed except in the middle of her course.
12But when we said that the sun moves sometimes in the ether, sometimes in the lower-world, it must be understood that the starry bodies, considered in relation to the universe, neither set nor rise; but only appear to do so to our sight on earth, which is suspended by the motion of some interior spirit, and compared with the immensity of things is but a little point, which causes the stars in their eternal order to appear sometimes fixed in heaven, and at others, from the imperfection of human vision, moving from their places. Let us now return to our original subject.