7.

Those, however, to whom I refer have inquired into these things with trustworthy calculations, so that they can not only state the reason of eclipses, both solar and lunar, but also predict their occurrence long before they take place, and are able to determine by mathematical computation the precise intervals at which these must happen, and to state the results in treatises, by reading and understanding which any others may foretell as well as they the coming of these eclipses, and find their prediction verified by the event. Such men,--and they deserve censure, as Holy Scripture teaches, because "though they had wisdom enough to measure the periods of this world, they did not much more easily come," as by humble piety they might have done, "to the knowledge of its Lord," ¹ --such men, I say, have inferred from the horns of the moon, which both in waxing and in waning are turned from the sun, either that the moon is illuminated by the sun, and that the farther it recedes from the sun the more fully does it lie exposed to its rays on the side which is visible from the earth; but that the more it approaches the sun, after the middle of the month, on the other half of its orbit, it becomes more fully illuminated on the upper part, and less and less open to receive the sun's rays on the side which is turned to the earth, and seems to us accordingly to decrease: or, that if the moon has light in itself, it has this light in the hemisphere on one side only, which side it gradually turns more to the earth as it recedes from the sun, until it is fully displayed, thereby exhibiting an apparent increase, not by the addition of what was deficient, but by disclosing what was already there; and that, in like manner, going towards the sun, the moon again gradually turns from our view that which had been disclosed, and so appears to decrease. Whichever of these two theories be correct, this at least is plain, and is easily discovered by any careful observer, that the moon does not to our eyes increase except when it is receding from the sun, nor decrease except when returning towards the sun.