Plutarch, De Iside et Osiride
Goodwin, Ed.

But now the priests do so abhor all kinds of superfluous excrements, that they not only decline most sorts of pulse, and of flesh that of sheep and swine, which produce much superfluity, but also in the time of their purgations they exclude salt from their meals. For which, as they have several other good reasons, so more especially this, that it whets the appetite and renders men over-eager after meat and drink. For that the reason why salt is not accounted clean should be (as Aristagoras tells us) because that, when it is hardened together, many little animals are catched in it and there die, is fond and ridiculous. They are also said to water the Apis from a well of his own, and to restrain him altogether from the river Nile,— not because they hold the water for polluted by reason of the crocodile, as some suppose, for there is nothing in the world in more esteem with the Egyptians than the Nile, [p. 69] but because the water of the Nile being drunk is observed to be very feeding, and above all others to conduce to the increase of flesh. But they would not have the Apis nor themselves neither to be over fat; but that their bodies should sit light and easy about their souls, and not press and squeeze them down by a mortal part overpowering and weighing down the divine.