Res Gestae

If, on the other hand, they stand in the nodes themselves which closely unite the ascent and the descent, the heaven will be overcast with thicker darkness, so that because of the density of the air we cannot see even objects which are near and close at hand.

Now it is thought that two suns are seen, if a cloud, raised higher than common and shining brightly from its nearness to the eternal fires,[*](I.e. the sun.) reflects a second brilliant orb, as if from a very clear mirror.

Let us now turn to the moon. Then only does she suffer a clear and evident eclipse, when, rounded out with her full light and opposite the sun, she is distant from its orb by 180 degrees (i.e. is in the seventh sign).[*](Of the Zodiac.) But although this happens at every full moon, yet there is not always an eclipse.