PROLOGUE. — 1. I have received the letter of your charity, my son Peter, in which you signified that you wished to journey to Jerusalem, and asked to be instructed by our writings as to what rule of the true faith you ought to hold in those parts, so that no sense of heretical falsehood might be able to creep upon you. I rejoice indeed that you bear such solicitude for guarding the true faith without any vice of perfidy, without which no conversion can profit, nay, cannot even exist. For the apostolic authority says that 'without faith it is impossible to please God' (Heb. 11:6). For faith is the foundation of all good things. Faith is the beginning of human salvation. Without it no one can belong to the number of the sons of God:
for without it no one in this world attains the grace of justification, nor in the world to come shall possess eternal life; and if anyone here does not walk by faith, he will not arrive at the sight [of God]. Without faith all the labor of man is empty. For it is just as if, without true faith, someone should wish to please God through contempt of the world: like someone who, journeying toward the homeland in which he knows he will live blessedly, abandons the straightness of the road and, being improvident, pursues the wandering path, by which he arrives not at the blessed city but falls into a precipice; where not joy is given to one arriving, but destruction is brought upon one falling. 2.
Nevertheless, that a sufficient discourse on faith may be brought forth, neither does the span of time favor it, since you desire quickly to have our answer, and so great is the work of this discussion that it can scarcely be fulfilled even by lengthy discourses. For you have not asked that you ought to be instructed on faith in such a way as to designate any one particular heresy, against which the intent of our discussion should specially keep watch:
but since you ask indefinitely for a definition of the faith, and desire it also to be concluded in brevity, you see beyond doubt how impossible it is for us to comprehend so great a matter fully in brief, for which we are not sufficient, even if we had so great a span of time and such genius that we could make many volumes on that which you require of us. But since God is near to all who call upon him in truth (Ps. 144:18), who making a full end and shortening [his word] has made it upon the earth (Rom. 9:28), I hope that, just as he has given you this holy solicitude for the faith, so also he will grant to me sufficient ability to serve your so good and so laudable desire:
so that even if I shall not be able to say all things by which every heretical error may be recognized, and, once recognized, may be either refuted or avoided, nevertheless, in the name and with the help of the holy Trinity, which is the one, sole, true, and good God, I shall say those things in which, at least in great part, it may be established that the reason of the catholic faith is contained without any fog of error. And these things being retained, you will also be able to detect and flee those which, even if in this work they are not seen to be refuted by special disputation, nevertheless from those things which here are set down generally and absolutely, may appear to be what unfaithful men wish (or are wont)
to whisper into the ears of the faithful, [things] not handed down by the rule of divine truth, but invented by the wickedness of human error. CHAPTER I. — 3. In whatever place, therefore, you shall be set, since, according to the rule promulgated by the command of our Savior, you know that you have been baptized in the one name of the Father and of the Son and of the Holy Spirit, hold principally and without doubt, with all your heart, that the Father is God, and the Son is God, and the Holy Spirit is God, that is, that the holy and ineffable Trinity is by nature one God; concerning whom it is said in Deuteronomy: 'Hear, O Israel, the Lord your God is one God (or, one Lord)' (Deut. 6:4). And, 'You shall adore the Lord your God, and him only shall you serve' (Ibid., 13).
Nevertheless, since we have said that this one God, who alone is by nature the true God, is not the Father alone, nor the Son alone, nor the Holy Spirit alone, but at once the Father and the Son and the Holy Spirit, care must be taken lest, just as we truly say that the Father and the Son and the Holy Spirit are one God, as regards natural unity, so we should dare to say—which is altogether wicked—that he who is the Father is the same as either the Son or the Holy Spirit; or that he who is the Son is either the Father or the Holy Spirit; or that he who is properly called the Holy Spirit in the confession of this Trinity is personally either the Father or the Son. 4.
For the faith which the holy patriarchs and prophets received divinely before the incarnation of the Son of God, which also the holy apostles heard from the Lord himself set in the flesh, and, instructed by the teaching of the Holy Spirit, not only preached by word but also left behind, embodied in their writings, for the most salutary instruction of posterity, preaches that one God is a Trinity, that is, the Father and the Son and the Holy Spirit. But there would not be a true Trinity if one and the same person were called Father and Son and Holy Spirit. For if, just as the substance of the Father and of the Son and of the Holy Spirit is one, so there were one person, there would be absolutely nothing in which a Trinity could truly be spoken of.
Again, there would indeed be a true Trinity, but that Trinity would not be one God, if, just as the Father and the Son and the Holy Spirit are distinguished from one another by the property of persons, so they had also been separated by a diversity of natures. But because in that one true God, the Trinity, not only that he is one God, but also that he is a Trinity, is naturally true, therefore that same true God is a Trinity in persons, and in one nature is one. Through this natural unity the whole Father is in the Son and the Holy Spirit, and the whole Son is in the Father and the Holy Spirit, and the whole Holy Spirit is in the Father and the Son. None of these is outside any of themselves (1 Sent., dist. 19, chap. 'Et inde'):
for no one either precedes another in eternity, or exceeds [another] in magnitude, or surpasses [another] in power. For as regards the unity of the divine nature, the Father is neither prior to, nor greater than, the Son or the Holy Spirit (Ibidem, chap. 'Nunc postquam'); nor can the eternity and immensity of the Son, as though prior or greater, either precede or exceed by nature the eternity and immensity of the Holy Spirit. As therefore neither is the Son posterior to or less than the Father, so neither is the Holy Spirit posterior to or less than the Son. For it is eternal and without beginning, that the Son came forth born of the nature of the Father; and it is eternal and without beginning, that the Holy Spirit proceeds from the nature of the Father and the Son.
For this reason, therefore, we rightly believe and say that the three are one God, because there is altogether one eternity, one immensity, and by nature one divinity of the three persons. 5. Let us hold, therefore, that the Father and the Son and the Holy Spirit are by nature one God; yet that the Father is not the same who is the Son, nor is the Son the same who is the Father, nor is the Holy Spirit the same who is the Father or the Son (1 Sent., dist. 2, chap. 'Omnes autem catholici'). For there is one essence of the Father and of the Son and of the Holy Spirit, which the Greeks call ousia, in which the Father is not one thing, and the Son another, and the Holy Spirit another, although personally the Father is one, the Son another, the Holy Spirit another.
This is chiefly shown to us at the very beginning of the holy Scriptures, where God says: 'Let us make man to our image and likeness' (Gen. 1:26). For when he says 'image' in the singular number, he shows that there is one nature, to whose image man was to be made. But when he says in the plural, 'our,' he shows that the same God, to whose image man was being made, is not one person. For if in that one nature of the Father and of the Son and of the Holy Spirit there were one person, it would not be said, 'to our image,' but 'to my image'; nor would he have said 'let us make,' but 'let me make.' But if in those three persons three substances were to be understood or believed, it would not be said, 'to our image,' but 'to our images':
for one image of three unequal natures could not exist. But since man is said to have been made according to the one image of the one God, the divinity of the holy Trinity is essentially intimated as one. Then, and a little after, in place of that which God had said above: 'Let us make man to our image and likeness,' Scripture thus narrated man as made, so that it said: 'And God made man: to the image of God he made him' (Gen. 1:27). 6. This Trinity of persons and unity of nature the prophet Isaiah did not keep silent as having been revealed to him, when he says that he saw the Seraphim crying out: 'Holy, holy, holy is the Lord God of hosts' (Isa. 6:3). Where indeed, in that it is said three times 'Holy,' [we recognize] the Trinity of persons;
but in that it is said once 'the Lord God of hosts,' we recognize the unity of the divine nature. In that holy Trinity, therefore, which is repeated by us for this reason, that it may be more tenaciously fixed in your heart, there is one Father, who alone essentially begot from himself one Son; and one Son, who alone was essentially born (or begotten) of one Father; and one Holy Spirit, who alone essentially proceeds from the Father and the Son. But this whole one person could not [do], that is, both to beget itself, and to be born of itself, and to proceed from itself. Since, therefore, to have begotten is other than to have been born, and to proceed (or to have proceeded)
is other than to have begotten or to have been born, it is manifest that the Father is one, the Son another, the Holy Spirit another. The Trinity, therefore, refers to the persons of the Father and of the Son and of the Holy Spirit; the unity, to the nature. CHAPTER II. The Humanity of Christ. — 7. As therefore, according to that divinity by which the Father and the Son and the Holy Spirit are one, we believe that neither the Father was born, nor the Holy Spirit, but the Son alone: so also, according to the flesh, the catholic faith both believes and preaches that the Son alone was born. For neither in that Trinity would it be proper to the Father alone that he himself was not born, but begot the one Son;
nor would it be proper to the Son alone that he himself did not beget, but was born alone of the essence of the Father; nor would it be proper to the Holy Spirit that he himself was neither born nor begot, but alone proceeds from the Father and the Son; if, according to the divine nature indeed, God the Father were born of no God, yet according to the flesh he himself were born of a virgin. For if the Father were born of a virgin, the Father and the Son would be one person: and that same one person, inasmuch as it would be born not of God, but only of a virgin, would truly be called not the Son of God, but only the son of man; nor would the very Son of God say: 'For God so loved the world, that he gave his only-begotten Son' (John 3:16); and again:
'For God did not send his Son into the world to judge the world, but that the world might be saved through him' (Ibid., 17). Nor would blessed John have said: 'He who loves the begetter loves also him who is born of him' (1 John 5:1); nor would the Son himself have said: 'My Father works until now, and I work' (John 5:17). For he who is called the Son, if he were also the same as the Father, would not truly be called the Son of God, because he would be born not of God, but only of a virgin. And at the last, the Father himself would not testify from heaven and point out his own Son with a bodily voice, saying: 'This is my beloved Son, in whom I am well pleased' (Matt. 3:17). Nor would the Apostle Paul have said concerning God the Father:
'Who did not spare his own Son, but delivered him up for us all' (Rom. 8:32). 8. But since all these things have both been spoken divinely for our instruction, and, because they have been divinely spoken, are certainly true, that is true which the catholic faith preaches: that according to the divinity the Son alone was born of the Father, eternal with the Father, immortal, impassible, and immutable God; and that according to the flesh not the Father, but his only-begotten Son, his eternity being preserved, was born in time; his impassibility being preserved, suffered; his immortality being preserved, died; his immutability being preserved—by which he is true God and eternal life—was truly raised up.
He has everything in common with the Father which, being naturally eternal, He possessed without beginning; and He has nothing in common with the Father among those things which that eternal and exalted One received into His own person in time and in lowliness. 9. Again, if it were not He who is the proper and only-begotten Son of God the Father, but rather the Holy Spirit, who was born of the Virgin, then the holy Church would not believe in her heart unto righteousness, nor confess with her mouth unto salvation, that very Son who was made of a woman, made under the law, born of the Holy Spirit from the Virgin Mary, received in the Creed.
But also, if the Holy Spirit Himself, who is the Spirit of the Father and of the Son, had taken the form of a servant, then the Holy Spirit Himself would not have descended from heaven in the form of a dove upon that Man whom He Himself had made. 10. Therefore God the Father, begotten of no God, once from His own nature begot without beginning the Son, God equal to Himself, and co-eternal in that same divinity by which He Himself is naturally eternal. But this same Son of God, though He is eternal and true God, and with the Father according to divinity naturally one God—according to that which He says: 'I and the Father are one' (John 10:30)—the same One for our sake was made a true and complete man. In Him true, because that God possesses a true human nature;
and in Him complete, because He took on both human flesh and a rational soul. Yet the same only-begotten God was born a second time: once of the Father, once of the mother; for God the Word was born of the Father, and the Word made flesh was born of the mother. 11. Therefore there is one and the same God, the Son of God, born before the ages and born in time; and both nativities belong to the one Son of God: the divine, according to which as Creator, in the form of God, He is God co-eternal with the Father;
the human, according to which, emptying Himself and taking the form of a servant, He not only formed Himself in the conception of the maternal womb by that same assumption of the servile form, while He became man, but also the same God made man went forth from that same womb of His mother, and the same God made man hung upon the cross, and the same God made man lay in the tomb, and the same God made man rose again from the dead on the third day; yet in the tomb the same God lay according to the flesh alone, and He descended into hell according to the soul alone. When He returned from the dead to the flesh on the third day, the same God, according to the flesh which lay in the tomb, rose again from the tomb;
and on the fortieth day after the resurrection, the same God made man, ascending into heaven, sat at the right hand of God, and from thence He will come at the end of the age to judge the living and the dead. 12. Therefore the Word made flesh is the one Son of God, the Lord Jesus Christ, the Mediator between God and men. And He is Mediator because He is at once the same true God and man, having with the Father one nature of divinity, and with the mother one substance of humanity; having from us, even unto death, the penalty of our iniquity; having from God the Father unchangeable righteousness; for the sake of our iniquity dying in time, but for the sake of His own righteousness Himself ever living, and about to bestow immortality upon mortals.
He preserved His perfect humanity in the very perfection of His divinity; yet the reality of His mortality, through the acceptance of death, He swallowed up by the reality and unchangeableness of His immortality. 13. This is what blessed Peter attests, that Christ swallowed up death, so that we might be made heirs of eternal life (cf. 1 Pet. 3:22). Blessed Paul also teaches that Christ swallowed up death, and brought to light life and incorruption (2 Tim. 1:10). Christ therefore tasted death, because He is true man; and the same One swallowed up death, because He is true God. For the same One, as the Apostle says, 'was crucified through weakness, yet lives by the power of God' (2 Cor. 13:4):
one and the same, who according to the prophecy of blessed David both was made man in Zion, and He Himself, the Most High, founded her (Ps. 87:5). Thus neither is the divinity of Christ foreign to the nature of the Father, according to that which says, 'In the beginning was the Word, and the Word was with God, and the Word was God. The same was in the beginning with God. All things were made through Him, and without Him nothing was made' (John 1:1-3); nor is His humanity foreign to the nature of the mother, according to that which says, 'The Word was made flesh, and dwelt among us' (ibid., 14). For that nature which always remains begotten of the Father took on our nature without sin, that He might be born of a virgin.
For an eternal and divine nature could in no way be conceived in time and born in time from a human nature, unless the ineffable divinity had, according to the assumption of true humanity, received in itself a true conception and nativity in time. Thus God, eternal and true, was truly both conceived and born of a virgin according to time. For when the fullness of time came, God sent His Son, made of a woman, made under the law, to redeem those who were under the law, that we might receive the adoption of sons (Gal. 4:4-5)—namely, that God who was naturally made the Son of man, who is naturally the one Son of God the Father. This indeed the Evangelist John confirms, when, after he had said,
'And the Word was made flesh, and dwelt among us' (John 1:14), he immediately adds, 'And we beheld His glory, the glory as of the Only-begotten of the Father, full of grace and truth' (ibid.). Thus He, the Creator and Lord of all spirits and all bodies, that is, of all natures, created the Virgin, being about to be created from the Virgin; and He made a mother for Himself of her whose maker He is, when, being about to be conceived and brought forth from her flesh, the boundless and everlasting God received the true matter of flesh: so that both according to the reality of the servile form God might mercifully become man, and according to the form of God, remaining the same God, He might not lack that man by natural reality. 15.
Thus therefore believe that Christ, the Son of God, that is, one Person of the Trinity, is true God, so that you do not doubt that His divinity was born of the nature of the Father; and thus believe Him to be true man, so that you do not think His flesh to be born of heaven, or of air, or of any other thing, but of that whose flesh belongs to all men: that is, the flesh which God Himself formed from the earth for the first man, and forms for the rest of men, whom He creates by propagation from men. But although the flesh of Christ and of all men is of one and the same nature, yet this flesh, which God the Word deigned to unite to Himself from the Virgin Mary, was conceived without sin and born without sin:
so that, precisely according to it, the eternal and just God was mercifully both conceived and born, and the Lord of glory was crucified. 16. The desire of intercourse. — But with what words shall be explained the singular excellence of that flesh, whose person is divine from its very conception, whose origin of nativity is unwonted, whereby the Word was so made flesh that the Only-begotten and everlasting God was one Person with His own flesh, being conceived by the very conception of His flesh? But that flesh of other men is certainly born through human intercourse, the man sowing the seed, the woman conceiving and bearing.
And because, when man and woman join together to beget children, the intercourse of the parents is not without lust, for this reason the conception of the children born of their flesh cannot be without sin, since it is not propagation but lust that transmits sin to little ones; nor does the fecundity of human nature cause men to be born with sin, but the foulness of lust, which men have from the most just condemnation of that first sin. Therefore blessed David, although he was born of a lawful and just marriage, in which indeed no fault of infidelity nor stain of fornication could be found:
yet on account of original sin, by which the children of wrath are naturally bound—not only the children of the impious, but also all who are born of the sanctified flesh of the just—he cries out and says: 'Behold, I was conceived in iniquities, and in sins did my mother bear me' (Ps. 51:5). Holy Job also says that man is not clean from filth, not even if his life upon earth be of one day (Job 14:4, according to the Septuagint). 17. The only-begotten Son of God, therefore, who is in the bosom of the Father, in order to cleanse the flesh and soul of man, was incarnate by the assumption of flesh and a rational soul; and He who is true God became true man, not that one should be God and another man, but the same God, the same man.
In order to take away that sin which the human race contracted in the intercourse of mortal flesh, He was conceived in a new manner, God incarnate in a virgin mother, without the union of a man, without the lust of the conceiving virgin: so that through the God-man, whom the inviolate womb of the virgin brought forth conceived without lust, might be washed away the sin which all men draw at birth—men for whom, in the body of this death, such is the condition of being born, that their mothers cannot fulfill the work of fecundity unless they first lose the virginity of the flesh.
The only-begotten God alone, therefore, took away the sin of human conception and nativity, who, while being conceived, received the reality of flesh from the virgin, and while being born, preserved the integrity of virginity in the mother. This is the reason why God became the son of the Virgin Mary, and Mary the virgin became the mother of the only-begotten God: so that Him whom the Father begot from eternity, the virgin might bring forth conceived in time—that virgin, indeed, whom God, who was to be born of her, so anticipated and filled with singular grace, that she might have as the fruit of her womb Him whom the whole universe has as its Lord from the beginning:
and she saw Him subject to herself by the solemn manner of being born, whom in the unity of the paternal substance not only human but also angelic creation acknowledges and adores as the Most High. 18. Thus therefore sin and the penalty of sin, which entered into the world through the crime of a corrupted woman, is taken away from the world through the childbearing of an inviolate virgin. And because in the condition of the human race it came about, through a woman who was made from a man alone, that we were held bound by the bond of death, this the divine goodness wrought in the redemption of the human race, that through a man who was born of a woman alone, life might be restored to men. There the devil, by his most wicked deception, associated human nature to himself in the likeness of sin;
here God took up human nature into the unity of His Person. There the woman was deceived, that she might become a daughter of the devil; here the virgin was filled with grace, that she might become the mother of the most high and unchangeable only-begotten God. There the angel, cast down through pride, gained possession of the mind of the seduced woman; here God, humbling Himself through mercy, being about to be born of her, filled the womb of the incorrupt virgin. For the Son of God, Jesus Christ, who was in the form of God (which He could not be unless He were born of the nature of the Father), Himself, according to apostolic teaching, 'emptied Himself, taking the form of a servant' (Phil. 2:7).
The form of a servant, therefore, that is, the nature of a servant, that God took into His own Person, and thus, being the Maker of men, was made in the likeness of men, and being found in fashion as a man, He humbled Himself, becoming obedient to the Father even unto death, even the death of the cross (ibid., 8). 19. Ponder therefore attentively this saying of the Apostle, and in it you will learn how you are to believe that the Lord Jesus Christ is the same God and man. Yet do not in Him either confound or divide the reality of both natures in one Person. When therefore you first hear of the Lord Jesus Christ that He was in the form of God, it behooves you to acknowledge and to hold most firmly that in that word 'form' the natural fullness ought to be understood.
In the form of God, therefore, was the Lord Jesus Christ, because He was always in the nature of God the Father, of whom He was born. Therefore He is of one nature with the Father, and equally with Him everlasting and boundless, equally immortal and unchangeable, equally invisible and inexpressible, equally good and just, equally compassionate and merciful, patient and full of mercy and truthful, equally strong and gentle, equally wise and almighty. 20. Accordingly, retain most firmly all these things which we have said of the Son of God, because, having all these things in unity of nature with the Father, He is without doubt equal to the Father. Wherefore the Apostle also, immediately adding, says:
'He thought it not robbery to be equal with God' (Phil. 2:6). For that equality of the Son with the Father in divinity was not of robbery, but of nature. Also those things which the Apostle consequently subjoins, saying that 'He emptied Himself, taking the form of a servant, being made in the likeness of men, and found in fashion as a man; and that He humbled Himself, becoming obedient unto death, even the death of the cross'—all these things receive concerning that only-begotten God, the Son of God, concerning that Word who is God, of whom the Evangelist says: 'In the beginning was the Word, and the Word was with God, and the Word was God' (John 1:1); concerning that Power of God and Wisdom of God, of which it is said to God: 'Thou hast made all things in wisdom' (Ps.