On the Christian Faith (De fide)

The Son is of one substance with the Father.

108. And now, your Majesty, with regard to the question of the substance, why need I tell you that the Son is of one substance with the Father, when we have read that the Son is the image of the Father's substance, that you may understand that there is nothing wherein, so far as Godhead is regarded, the Son differs from the Father.

109. In virtue of this likeness Christ said: “All things that the Father has are Mine.” We cannot, then, deny substance to God, for indeed He is not unsubstantial, Who has given to others the ground of their being, though this be different in God from what it is in the creature. The Son of God, by Whose agency all things endure, could not be unsubstantial.

110. And therefore, the Psalmist says: “My bones are not hidden, which You made in secret, and my substance in the underworld.” For to His power and Godhead, the things that before the foundation of the world were done, though their magnificence was [as yet] invisible, could not be hidden. Here, then, we find mention of “substance.”

111. But it may be objected that the mention of His substance is the consequence of His Incarnation. I have shown that the word “substance” is used more than once, and that not in the sense of inherited possessions, as you would construe it. Now, if it please you, let us grant that, in accordance with the mystic prophecy, the substance of Christ was present in the underworld— for truly He did exert His power in the lower world to set free, in the soul which animated His own body, the souls of the dead, to loose the bands of death, to remit sins.

112. And, indeed, what hinders you from understanding, by that substance, His divine substance, seeing that God is everywhere, so that it has been said to Him: “If I go up into heaven, You are there; if I go down into hell, You are present.”

113. Furthermore, the Psalmist has in the words following made it plain that we must understand the divine substance to be mentioned when he says: “Your eyes did see My being, [as] not the effect of working;” inasmuch as the Son is not made, nor one of God's works, but the begotten Word of eternal power. He called Him “ἀχατέργαστον,” meaning that the Word neither made nor created, is begotten of the Father without the witnessing presence of any created being. Howbeit, we have abundance of testimony besides this. Let us grant that the substance here spoken of is the bodily substance, provided you also yourself say not that the Son of God is something effected by working, but confess His uncreated Godhead.

114. Now I know that some assert that the mystic incarnate form was uncreated, forasmuch as nothing was done therein through intercourse with a man, because our Lord was the offspring of a virgin. If, then, many have, on the strength of this passage, asserted that neither that which was brought forth of Mary was produced by creative operation, dare you, disciple of Arius, think that the Word of God is something so produced?

115. But is this the only place where we read of “substance”? Hath it not also been said in another passage: “The gates of the cities are broken down, the mountains are fallen, and His substance is revealed”? What, does the word mean something created here also? Some, I know, are accustomed to say that the substance is substance in money. Then, if you give this meaning to the word, the mountains fell, in order that some one's possessions of money might be seen.

116. But let us remember what mountains fell, those, namely, of which it has been said: “If you shall have faith as a grain of mustard seed you shall say to this mountain: Be removed, and be cast into the sea!” By mountains, then, are meant high things that exalt themselves.

117. Moreover, in the Greek, the rendering is this: “The palaces are fallen.” What palaces, save the palace of Satan, of whom the Lord said: “How shall His kingdom stand?” We are reading, therefore, of the things which are the devil's palaces as being very mountains, and therefore in the fall of those palaces from the hearts of the faithful, the truth stands revealed, that Christ, the Son of God, is of the Father's eternal substance. What, again, are those mountains of bronze, from the midst of which four chariots come forth?

118. We behold that height, lifting up itself against the knowledge of God, cast down by the word of the Lord, when the Son of God said: “Hold your peace, and come forth, you foul spirit.” Concerning whom the prophet also said: “Behold, I have come to you, you mount of corruption!”

119. Those mountains, then, are fallen, and it is revealed that in Christ was the substance of God, in the words of those who had seen Him: “Truly You are the Son of God,” for it was in virtue of divine, not human power, that He commanded devils. Jeremiah also says: “Make mourning upon the mountains, and beat your breasts upon the desert tracks, for they have failed; forasmuch as there are no men, they have not heard the word of substance: from flying fowl to beasts of burden, they trembled, they have failed.”

120. Nor has it escaped us, that in another place also, setting forth the frailties of man's estate, in order to show that He had taken upon Himself the infirmity of the flesh, and the affections of our minds, the Lord said, by the mouth of His prophet: “Remember, O Lord, what My substance is,” because it was the Son of God speaking in the nature of human frailty.

121. Of Him the Scripture says, in the passage cited, in order to discover the mysteries of the Incarnation: “But You have rejected, O Lord, and counted for nought— You have cast out Your Christ. You have overthrown the covenant made with Your Servant, and trampled His holiness in the earth.” What was it, in regard whereof the Scripture called Him “Servant,” but His flesh?— seeing that “He did not hold equality with God as a prey, but emptied Himself, taking the form of a servant, being made into the likeness of men, and found in fashion as a man.” So, then, in that He took upon Himself My nature, He was a servant, but by virtue of His own power He is the Lord.

122. Furthermore, what means it that you read, “Who has stood in the truth (substantia) of the Lord?” and again: “Now if they had stood in My truth, and had given ear to My words, and had taught My people, I would have turned them from their follies and transgressions”?