Against Praxeas by Tertullian
Chapter X.--The Very Names of Father and Son Prove the Personal Distinction of the Two They Cannot Possibly Be Identical, Nor is Their Identity Necessary to Preserve the Divine Monarchy.
So it is either the Father or the Son, and the day is not the same as the night; nor is the Father the same as the Son, in such a way that Both of them should be One, and One or the Other should be Both, -- an opinion which the most conceited |Monarchians| maintain. He Himself, they say, made Himself a Son to Himself. Now a Father makes a Son, and a Son makes a Father; and they who thus become reciprocally related out of each other to each other cannot in any way by themselves simply become so related to themselves, that the Father can make Himself a Son to Himself, and the Son render Himself a Father to Himself. And the relations which God establishes, them does He also guard. A father must needs have a son, in order to be a father; so likewise a son, to be a son, must have a father. It is, however, one thing to have, and another thing to be. For instance, in order to be a husband, I must have a wife; I can never myself be my own wife. In like manner, in order to be a father, I have a son, for I never can be a son to myself; and in order to be a son, I have a father, it being impossible for me ever to be my own father. And it is these relations which make me (what I am), when I come to possess them: I shall then be a father, when I have a son; and a son, when I have a father. Now, if I am to be to myself any one of these relations, I no longer have what I am myself to be: neither a father, because I am to be my own father; nor a son, because I shall be my own son. Moreover, inasmuch as I ought to have one of these relations in order to be the other; so, if I am to be both together, I shall fail to be one while I possess not the other. For if I must be myself my son, who am also a father, I now cease to have a son, since I am my own son. But by reason of not having a son, since I am my own son, how can I be a father? For I ought to have a son, in order to be a father. Therefore I am not a son, because I have not a father, who makes a son. In like manner, if I am myself my father, who am also a son, I no longer have a father, but am myself my father. By not having a father, however, since I am my own father, how can I be a son? For I ought to have a father, in order to be a son. I cannot therefore be a father, because I have not a son, who makes a father. Now all this must be the device of the devil -- this excluding and severing one from the other -- since by including both together in one under pretence of the Monarchy, he causes neither to be held and acknowledged, so that He is not the Father, since indeed He has not the Son; neither is He the Son, since in like manner He has not the Father: for while He is the Father, He will not be the Son. In this way they hold the Monarchy, but they hold neither the Father nor the Son. Well, but |with God nothing is impossible.| True enough; who can be ignorant of it? Who also can be unaware that |the things which are impossible with men are possible with God?| |The foolish things also of the world hath God chosen to confound the things which are wise.| We have read it all. Therefore, they argue, it was not difficult for God to make Himself both a Father and a Son, contrary to the condition of things among men. For a barren woman to have a child against nature was no difficulty with God; nor was it for a virgin to conceive. Of course nothing is |too hard for the Lord.| But if we choose to apply this principle so extravagantly and harshly in our capricious imaginations, we may then make out God to have done anything we please, on the ground that it was not impossible for Him to do it. We must not, however, because He is able to do all things suppose that He has actually done what He has not done. But we must inquire whether He has really done it. God could, if He had liked, have furnished man with wings to fly with, just as He gave wings to kites. We must not, however, run to the conclusion that He did this because He was able to do it. He might also have extinguished Praxeas and all other heretics at once; it does not follow, however, that He did, simply because He was able. For it was necessary that there should be both kites and heretics; it was necessary also that the Father should be crucified. In one sense there will be something difficult even for God -- namely, that which He has not done -- not because He could not, but because He would not, do it. For with God, to be willing is to be able, and to be unwilling is to be unable; all that He has willed, however, He has both been able to accomplish, and has displayed His ability. Since, therefore, if God had wished to make Himself a Son to Himself, He had it in His power to do so; and since, if He had it in His power, He effected His purpose, you will then make good your proof of His power and His will (to do even this) when you shall have proved to us that He actually did it.