Leo, bishop of the city of Rome to his well-beloved brother, Julian the bishop.
Although by the hands of our brothers, whom we have despatched from the city on behalf of the Faith, we hare sent a most full refutation of Eutyches' excessive heresy to our brother Flavian, yet because we have received, through our son Basil, your letter, beloved, which has given us much pleasure from the fervour of its catholic spirit, we have added this page also which agrees with the other document, that you may offer a united and strenuous resistance to those who seek to corrupt the gospel of Christ, since the wisdom and the teaching of the Holy Spirit is one and the same in you as in us: and whosoever does not receive it, is not a member of Christ's body and cannot glory in that Head in which he denies the presence of his own nature. What advantage is it to that most unwise old man under the name of the Nestorian heresy to mangle the belief of those, whose most devout faith he cannot tear to pieces: when in declaring the only-begotten Son of God to have been so born of the blessed Virgin's womb that He wore the appearance of a human body without the reality of human flesh being united to the Word, he departs as far from the right path as did Nestorius in separating the Godhead of the Word from the substance of His assumed Manhood(2) ? From which prodigious falsehood who does not see what monstrous opinions spring? for he who denies the true Manhood of Jesus Christ, must needs be filled with many blasphemies, being claimed by Apollinaris as his own, seized upon by Valentinus, or held fast by Manichaeus: none of whom believed that there was true human flesh in Christ. But, surely, if that is not accepted, not only is it denied that He. who was in the form of God, but yet abode in the form of a slave, was born Man according to the flesh and reasonable soul: but also that He was crucified, dead, and buried, and that on the third day He rose again, and that, sitting at the right hand of the Father, he will come to judge the quick and the dead(3) in that body in which He Himself was judged,: because these pledges(4) of our redemption are rendered void if Christ is not believed to have the true and whole nature of true Manhood.
Or because the signs of His Godhead were undoubted, shall the proof of his having a human body be assumed false, and thus theindications of both natures be accepted to prove Him Creator, but not be accepted for the salvation of the creature(5) ? No, for the flesh did not lessen what belongs to His Godhead, nor the Godhead destroy what belongs to His flesh. For He is at once both eternal from His Father and temporal from His mother, inviolable in His strength, possible in our weakness: in the Triune Godhead, of one and the same substance with the Father and the Holy Spirit, but in taking Manhood on Himself, not of one substance but of one and the same person [so that He was at once rich in poverty, almighty in submission, impossible in punishment, immortal in death(6) ]. For the Word was not in any part of It turned either into flesh or into soul, seeing that the absolute and unchangeable nature of the Godhead is ever entire in its Essence, receiving no loss nor increase, and so beatifying the nature that It had assumed that that nature remained for ever glorified in the person of the Glorifier. [But why should it seem unsuitable or impossible that the Word and flesh and soul should be one Jesus Christ, and that the Son of God and the Son of Man should be one, if flesh and soul which are of different natures make one person even without the Incarnation of the Word: since it is much easier for the power of the Godhead to produce this union of Himself and man than for the weakness of manhood by itself to effect it in its own substance.] Therefore neither was the Word changed into flesh nor flesh into the Word: but both remains in one and one is in both, not divided by the diversity and not confounded by intermixture: He is not one by His Father and another by His mother, but the same, in one way by His Father before every beginning, and in another by His mother at the end of the ages: so that He was "mediator between God and men, the man Christ Jesus(7) ," in whom dwelt "the fulness of the Godhead bodily(8) :" because it was the assumed (nature) not the Assuming (nature) which was raised, because God "exalted Him and gave Him the Name which is above every name: that in the name of Jesus every knee should bow, of things in heaven and things on earth and things under the earth, and that every tongue should confess that Jesus Christ the Lord is in the glory of God the Father(9) ."
[But as to that which Eutyches dared to say in the court of bishops "that before the Incarnation there were two natures in Christ, but after the Incarnation one(10) ,"he ought to have been pressed by the frequent and anxious questions of the judges to render an account of his acknowledgment, lest it should be passed over as something trivial, though it was seen to have issued from the same fount as his other poisonous opinions. For I think that in saying this he was convinced that the soul, which the Saviour assumed, had had its abode in the heavens before He was born of the Virgin Mary, and that the Word joined it to Himself in the womb. But this is intolerable to catholic minds and ears: because the Lord who came down from heaven brought with Him nothing that belonged to our state: for He did not receive either a soul which had existed before nor a flesh which was not of his mother's body. Undoubtedly our nature was not assumed in such a way that it was created first and then assumed, but it was created by the very assumption. And hence that which was deservedly condemned in Origen must be punished in Eutyches also, unless he prefers to give up his opinion, viz. the assertion that souls have had not only a life but also different actions before they were inserted in men's bodies(11) ]. For although the Lord's nativity according to the flesh has certain characteristics wherein it transcends the ordinary beginnings of man's being, both because He alone was conceived and born without concupiscence of a pure Virgin, and because He was so brought forth of His mother's womb that her fecundity bare Him without loss of virginity: yet His flesh was not of another nature to ours: nor was the soul breathed into Him from another source to that of all other men, and it excelled others not in difference of kind but in superiority of power. For He had no opposition in His flesh [nor did the strife of desires give rise to a conflict of wishes(12) ]. His bodily senses were active without the law of sin, and the reality of His emotions being under the control of His Godhead and His mind, was neither assaulted by temptations nor yielded to injurious influences. But true Man was united to God and was not brought down from heaven as regards a pro-existing soul, nor created out of nothing as regards the flesh: it wore the same person in the Godhead of the Word and possessed a nature in common with us in its body and soul. For He would not be "the mediator between God and man," unless God and man had co-existed in both natures forming one true Person. The magnitude of the subject urges us to a lengthy discussion: but with one of your learning there is no need for such copious dissertations, especially as we have already sent a sufficient letter to our brother Flavian by our delegates for the confirmation of the minds, not only of priests but also of the laity. The mercy of God will, we believe, provide that without the loss of one soul the sound may be defended against the devil's wiles, and the wounded healed. Dated 13th June in the consulship of the illustrious Asturius and Protogenes (449).