In the case of the Saturnalia he put back the fifth day which had been appointed by Gaius but was later abolished. [-26-] and inasmuch as the sun was to undergo an eclipse on his birthday, he feared that some disturbance might result,—for already certain other portents had occurred,—and therefore he gave notice beforehand not only that there would be an eclipse and when and for how long, but also the reasons for which this would necessarily take place. They are as follows:
The moon, which revolves lower down than the sun (or so it is believed), either directly below him or perhaps with Mercury and likewise Venus intervening, has a longitudinal movement just like him, and a higher and lower movement just like him, but furthermore a latitudinal movement such as nowhere belongs to the sun under any circumstances. When, therefore, she gets in a direct line with him over our heads and passes under his blaze, then she obscures his beams that extend toward the earth, for some to a greater, for some to a less degree, but does not conceal his presence for even the briefest moment. For since the sun has a light of his own he can never surrender it, and consequently, when the moon is not directly in people’s way so as to throw a shadow over him, he always appears entire.
This, then, is what happens to the sun and it was made public by Claudius at the time mentioned. With regard to the moon, however,—for it is not irrelevant to speak of lunar phenomena also, since once I have broached this subject,—as often as she gets directly opposite the sun (and she only takes such a position with reference to him at full moon, whereas he takes it with reference to her at the season of new moon), a conical shadow falls upon the earth. This occurs whenever in her motion to and from us her revolution takes her between the sun and the earth; then she is deprived of the sun’s light and appears by herself just as she really is. Such are the conditions of the case.