The Word perceived that corruption could not be got rid of otherwise than through death; yet He Himself, as the Word, being immortal and the Father's Son, was such as could not die. For this reason, therefore, He assumed a body capable of death, in order that it, through belonging to the Word Who is above all, might become in dying a sufficient exchange for all, and, itself remaining incorruptible through His indwelling, might afterward put an end to corruption for all others as well, by the grace of the resurrection. It was by surrendering to death the body which He had taken, as an offering and sacrifice free from every stain, that He immediately abolished death for His human brethren by the offering of the equivalent.
For naturally, since the Word of God was above all, when He offered His own temple and bodily instrument as a substitute for the life of all, He fulfilled in death all that was required. Naturally also, through this union of the immortal Son of God with our human nature, all men were clothed with incorruption in the promise of the resurrection. For the solidarity of humanity is such that, by virtue of the Word's indwelling in a single human body, the corruption which goes with death has lost its power over all.
It is like a great king entering a large city and dwelling in one of its houses. The whole city is then judged worthy of great honor, and no enemy or robber attacks and destroys it. Instead, the city receives even greater care because the king dwells in one of its houses. So it has also been with the King of all.
For when He came into our realm and dwelt in one body like our own, every plot of the enemies against humanity was brought to an end, and the corruption of death, which had formerly held power over human beings, disappeared. The human race would have been utterly lost if the Lord and Savior of all, the Son of God, had not come to bring death to an end.