(44) It may be, however, that, though shamed into agreeing that this objection is void, the Greeks will want to raise another. They will say that, if God wanted to instruct and save mankind, He might have done so, not by His Word's assumption of a body, but, even as He at first created them, by the mere signification of His will. The reasonable reply to that is that the circumstances in the two cases are quite different. In the beginning, nothing as yet existed at all; all that was needed, therefore, in order to bring all things into being, was that His will to do so should be signified. But once man was in existence, and things that were, not things that were not, demanded to be healed, it followed as a matter of course that the Healer and Savior should align Himself with those things that existed already, in order to heal the existing evil. For that reason, therefore, He was made man, and used the body as His human instrument. If this were not the fitting way, and He willed to use an instrument at all, how otherwise was the Word to come? And whence could He take His instrument, save from among those already in existence and needing His Godhead through One like themselves? It was not things non-existent that needed salvation, for which a bare creative word might have sufficed, but man--man already in existence and already in process of corruption and ruin. It was natural and right, therefore, for the Word to use a human instrument and by that means unfold Himself to all.
You must know, moreover, that the corruption which had set in was not external to the body but established within it. The need, therefore, was that life should cleave to it in corruption's place, so that, just as death was brought into being in the body, life also might be engendered in it. If death had been exterior to the body, life might fittingly have been the same. But if death was within the body, woven into its very substance and dominating it as though completely one with it, the need was for Life to be woven into it instead, so that the body by thus enduing itself with life might cast corruption off. Suppose the Word had come outside the body instead of in it, He would, of course, have defeated death, because death is powerless against the Life. But the corruption inherent in the body would have remained in it none the less. Naturally, therefore, the Savior assumed a body for Himself, in order that the body, being interwoven as it were with life, should no longer remain a mortal thing, in thrall to death, but as endued with immortality and risen from death, should thenceforth remain immortal. For once having put on corruption, it could not rise, unless it put on life instead; and besides this, death of its very nature could not appear otherwise than in a body. Therefore He put on a body, so that in the body He might find death and blot it out. And, indeed, how could the Lord have been proved to be the Life at all, had He not endued with life that which was subject to death? Take an illustration. Stubble is a substance naturally destructible by fire; and it still remains stubble, fearing the menace of fire which has the natural property of consuming it, even if fire is kept away from it, so that it is not actually burnt. But suppose that, instead of merely keeping the fire from it somebody soaks the stubble with a quantity of asbestos, the substance which is said to be the antidote to fire. Then the stubble no longer fears the fire, because it has put on that which fire cannot touch, and therefore it is safe. It is just the same with regard to the body and death. Had death been kept from it by a mere command, it would still have remained mortal and corruptible, according to its nature. To prevent this, it put on the incorporeal Word of God, and therefore fears neither death nor corruption any more, for it is clad with Life as with a garment and in it corruption is clean done away.
Edition opa.patristics.athanasius-of-alexandria.on-the-incarnation.en.