Irenaeus
"We may undermine [the Hellenists’] doctrine as to transmigration from body to body by this fact—that souls remember nothing whatever of the events which took place in their previous states of existence. For if they were sent forth with this object, that they should have experience of every kind of action, they must of necessity retain a remembrance of those things which have been previously accomplished, that they might fill up those in which they were still deficient, and not by always hovering, without intermission, through the same pursuits, spend their labor wretchedly in vain. . . . With reference to these objections, Plato . . . attempted no kind of proof, but simply replied dogmatically that when souls enter into this life they are caused to drink of oblivion by that demon who watches their entrance, before they effect an entrance into the bodies. It escaped him that he fell into another, greater perplexity. For if the cup of oblivion, after it has been drunk, can obliterate the memory of all the deeds that have been done, how, O Plato, do you obtain the knowledge of this fact . . . ?" (Against Heresies 2:33:1–2 [A.D. 189]).
Tertullian
"Come now, if some philosopher affirms, as Laberius holds, following an opinion of Pythagoras, that a man may have his origin from a mule, a serpent from a woman, and with skill of speech twists every argument to prove his view, will he not gain an acceptance for it [among the pagans], and work in some conviction that on account of this, they should abstain from eating animal food? May anyone have the persuasion that he should abstain, lest, by chance, in his beef he eats some ancestor of his? But if a Christian promises the return of a man from a man, and the very actual Gaius [resurrected] from Gaius . . . they will not . . . grant him a hearing. If there is any ground for the moving to and fro of human souls into different bodies, why may they not return to the very matter they have left . . . ?" (Apology 48 [A.D. 197]).
Origen
"But if . . . the Greeks, who introduce the doctrine of transmigration, laying down things in harmony with it, do not acknowledge that the world is coming to corruption, it is fitting that when they have looked the scriptures straight in the face which plainly declare that the world will perish, they should either disbelieve them or invent a series of arguments in regard to the interpretation of things concerning the consummation; which even if they wish they will not be able to do" (Commentary on Matthew 10:20 [A.D. 248]).
Arnobius
"[M]an’s real death [is] when souls which know not God shall be consumed in long-protracted torment with raging fire, into which certain fiercely cruel beings shall cast them. . . . Wherefore, there is no reason that [one] should mislead us, should hold our vain hopes to us, which some men say is unheard of till now, and carried away by an extravagant opinion of themselves, that souls are immortal, next in point of rank to the God and ruler of the world, descended from that Parent and Sire. . . . [And] while we are moving swiftly down toward our mortal bodies, causes pursue us from the world’s circles, through the working of which we become bad—aye, most wicked . . . [and] that the souls of wicked men, on leaving their human bodies, pass into cattle and other creatures" (Against the Pagans 2:14–15 [A.D. 305]).
Lactantius
"What of Pythagoras, who was first called a philosopher, who judged that souls were indeed immortal, but that they passed into other bodies, either of cattle or of birds or of beasts? Would it not have been better that they should be destroyed, together with their bodies, than thus to be condemned to pass into the bodies of other animals? Would it not be better not to exist at all than, after having had the form of a man, to live as a swine or a dog? And the foolish man, to gain credit for his saying, said that he himself had been Euphorbus in the Trojan war, and that when he had been slain he passed into other figures of animals, and at last became Pythagoras. O happy man!—to whom alone so great a memory was given! Or rather unhappy, who when changed into a sheep was not permitted to be ignorant of what he was! And [I] would to heaven that he [Pythagoras] alone had been thus senseless!" (Epitome of the Divine Institutes 36 [A.D. 317]).
Gregory of Nyssa
"[I]f one should search carefully, he will find that their doctrine is of necessity brought down to this. They tell us that one of their sages said that he, being one and the same person, was born a man, and afterward assumed the form of a woman, and flew about with the birds, and grew as a bush, and obtained the life of an aquatic creature—and he who said these things of himself did not, so far as I can judge, go far from the truth, for such doctrines as this—of saying that one should pass through many changes—are really fitting for the chatter of frogs or jackdaws or the stupidity of fishes or the insensibility of trees" (The Making of Man 28:3 [A.D. 379]).
Ambrose of Milan
"It is a cause for wonder that though they [the heathen] . . . say that souls pass and migrate into other bodies. . . . But let those who have not been taught doubt [the resurrection]. For us who have read the law, the prophets, the apostles, and the gospel, it is not lawful to doubt" (Belief in the Resurrection 65–66 [A.D. 380]).
"But is their opinion preferable who say that our souls, when they have passed out of these bodies, migrate into the bodies of beasts or of various other living creatures? . . . For what is so like a marvel as to believe that men could have been changed into the forms of beasts? How much greater a marvel, however, would it be that the soul which rules man should take on itself the nature of a beast so opposed to that of man, and being capable of reason should be able to pass over to an irrational animal, than that the form of the body should have been changed?" (ibid., 127).
John Chrysostom
"As for doctrines on the soul, there is nothing excessively shameful that they [the disciples of Plato and Pythagoras] have left unsaid, asserting that the souls of men become flies and gnats and bushes and that God himself is a [similar] soul, with some other the like indecencies. . . . At one time he says that the soul is of the substance of God; at another, after having exalted it thus immoderately and impiously, he exceeds again in a different way, and treats it with insult, making it pass into swine and asses and other animals of yet less esteem than these" (Homilies on John 2:3, 6 [A.D. 391]).
Basil the Great
"[A]void the nonsense of those arrogant philosophers who do not blush to liken their soul to that of a dog, who say that they have themselves formerly been women, shrubs, or fish. Have they ever been fish? I do not know, but I do not fear to affirm that in their writings they show less sense than fish" (The Six Days’ Work 8:2 [A.D. 393]).