Plutarch De Iside et Osiride 8

[8] Nothing that is irrational or fabulous or prompted by superstition, as some believe, has ever been given a place in their rites, but in them are some things that have moral and practical values, and others that are not without their share in the refinements of history or natural science, as, for example, that which has to do with the onion. For the tale that Dictys, the nurseling of Isis, in reaching for a clump of onions, fell into the river and was drowned is extremely incredible. But the priests keep themselves clear of the onion ¹ and detest it and are careful to avoid it, because it is the only plant that naturally thrives and flourishes in the waning of the moon. It is suitable for neither fasting nor festival, because in the one case it causes thirst and in the other tears for those who partake of it.

In like manner they hold the pig to be an unclean animal, ² because it is reputed to be most inclined to mate in the waning of the moon, and because the bodies of those who drink its milk break out with leprosy and scabrous itching. ³ The story which they relate at their only sacrifice and eating of a pig at the time of the full moon, how Typhon, while he was pursuing a boar by the light of the full moon, found the wooden coffin in which lay the body of Osiris, which he rent to pieces and scattered, ⁴ they do not all accept, believing it to be a misrepresentation, even as many other things are.

Moreover, they relate that the ancient Egyptians put from them luxury, lavishness, and self-indulgence, to such a degree that they used to say that there was a pillar standing in the temple at Thebes which had inscribed upon it curses against Meinis, ⁵ their king, who was the first to lead the Egyptians to quit their frugal, thrifty, and simple manner of living. It is said also that Technactis, ⁶ the father of Bocchoris, ⁷ when he was leading his army against the Arabians, because his baggage was slow in arriving, found pleasure in eating such common food as was available, and afterwards slept soundly on a bedding of straw, and thus became fond of frugal living; as the result, he invoked a curse on Meinis, and, with the approval of the priests, had a pillar set up with the curse inscribed upon it.

[8] For nothing hath been ranked among their sacred and religious rites that savored of folly, romance, or superstition, as some do suppose; but some of them were such as contained some signification of morality and utility, and others such as were not without a fineness either in history or natural philosophy. As, for instance, in what refers to the onions; for that Dictys, the foster-father of Isis, as he was reaching at a handful of onions, fell into the river and was there drowned, is extremely improbable. But the true reason why the priests abhor, detest, and avoid the onion is because it is the only plant whose nature it is to grow and spread forth in the wane of the moon. Besides, it is no proper food, either for such as would practise abstinence and use purgations, or for such as would observe the festivals; for the former, because it causeth thirst, and for the latter, because it forceth tears from those that eat it. They likewise esteem the swine as an unhallowed animal, because it is observed to be most apt to engender in the wane of the moon, and because that such as drink its milk have a leprosy and scabbed roughness in their bodies. But the story which they that sacrifice a swine at every full moon are wont to subjoin after their eating of it, — how that Typhon, being once about the full of the moon in pursuit of a certain swine, found by chance the wooden chest wherein lay the body of Osiris, and scattered it, — is not received by all, but looked upon as a misrepresented story, as a great many more such are. They tell us moreover, that the ancients did so much despise delicacy, sumptuousness, and a soft and effeminate way of living, that they erected a pillar in the temple at Thebes, having engraven upon it several grievous curses against King Meinis, who (as they tell us) was the first that brought off the Egyptians from a mean, wealthless, and simple way of living. There goes also another story, how that Technatis, father to Bocchoris, commanding an army against the Arabians, and his baggage and provisions not coming in as soon as was expected, heartily fed upon such things as he could next light on, and afterwards had a sound sleep upon a pallet, whereupon he fell greatly in love with a poor and mean life; and for this reason he cursed Meinis, and that with the consent of all the priests, and carved that curse upon a pillar.