Plato, Republic

[381a] “Certainly.” “And is it not the soul that is bravest and most intelligent, that would be least disturbed¹ and altered by any external affection?” “Yes.” “And, again, it is surely true of all composite implements, edifices, and habiliments, by parity of reasoning, that those which are well made and in good condition are least liable to be changed by time and other influences.” “That is so.” “It is universally² true, then, that that which is in the best state by nature or [381b] art or both admits least alteration by something else.” “So it seems.” “But God, surely, and everything that belongs to God is in every way in the best possible state.” “Of course.” “From this point of view, then, it would be least of all likely that there would be many forms in God.” “Least indeed.”

“But would he transform and alter himself?” “Obviously,” he said, “if he is altered.” “Then does he change himself for the better and to something fairer, or for the worse³ and to something uglier than himself?” [381c] “It must necessarily,” said he, “be for the worse if he is changed. For we surely will not say that God is deficient in either beauty or excellence.” “Most rightly spoken,” said I. “And if that were his condition, do you think, Adeimantus, that any one god or man would of his own will worsen himself in any way?” “Impossible,” he replied. “It is impossible then,” said I, “even for a god to wish to alter himself, but, as it appears, each of them being the fairest and best possible abides⁴ for ever simply in his own form.” “An absolutely necessary conclusion to my thinking.” “No poet then,” [381d] I said, “my good friend, must be allowed to tell us that “ The gods, in the likeness of strangers,
Many disguises assume as they visit the cities of mortals.
”Hom. Od. 17.485-486⁵ Nor must anyone tell falsehoods about Proteus⁶ and Thetis, nor in any tragedy or in other poems bring in Hera disguised as a priestess collecting alms“ for the life-giving sons of Inachus, the Argive stream.
”Aesch.⁷ [381e] And many similar falsehoods they must not tell. Nor again must mothers under the influence of such poets terrify their children⁸ with harmful tales, how that there are certain gods whose apparitions haunt the night in the likeness of many strangers from all manner of lands, lest while they speak evil of the gods they at the same time make cowards of children.” “They must not,” he said. “But,” said I, “may we suppose that while the gods themselves are incapable of change they cause us to fancy that they appear in many shapes deceiving and practising magic upon us?” “Perhaps,” said he. “Consider,”