Plutarch, De Iside et Osiride
Frank Cole Babbitt, Ed.

There are some who would make the legend an allegorical reference to matters touching eclipses ; for the Moon suffers eclipse only when she is full, with the Sun directly opposite to her, and she falls into the shadow of the Earth, as they say Osiris fell into his coffin. Then again, the Moon herself obscures the Sun and causes solar eclipses, always on the thirtieth of the month ; however, she does not completely annihilate the Sun, and likewise Isis did not annihilate Typhon.

When Nephthys gave birth to Anubis, Isis treated the child as if it were her own¹; for Nephthys is that which is beneath the Earth and invisible, Isis that which is above the earth and visible ; and the circle which touches these, called the horizon, being common to both,² has received the name Anubis, and is represented in form like a dog ; for the dog can see with his eyes both by night and by day alike. And among the Egyptians Anubis is thought to possess this faculty, which is similar to that which Hecatê is thought to possess among the Greeks, for Anubis is a deity of the lower world as well as a god of Olympus. Some are of the opinion that Anubis is Cronus. For this reason, inasmuch as he generates all things out of himself and conceives all things within himself, he has gained the appellation of ‘Dog.’ ³ There is, therefore, a certain mystery observed by those who revere Anubis; in ancient times the dog obtained the highest honours in Egypt; but, when Cambyses⁴ had slain the Apis and cast him forth, nothing came near the body or ate of it save only the dog ; and thereby the dog lost his primacy and his place of honour above that of all the other animals. [p. 109]

There are some who give the name of Typhon to the Earth's shadow, into which they believe the moon slips when it suffers eclipse.⁵