15 And concerning all this that I have explained to you, that those dead persons were raised with two words each, it was because for them two resurrections take place; that former one, and the second, that which is to come. For in that resurrection in which all men shall rise, none shall fall again; and by one word of God, sent forth through Christ, all the dead shall rise in the twinkling of an eye, speedily. For He Who brings it to pass is not feeble or insufficient.
For with one word of summons He will cause all the ends (of the world) to hear, and all that are laid (in the grave) shall leap forth and rise up; and no word shall return void to Him that sent it forth, but as it is written in the Prophet Isaiah, who compares the word to rain and snow; for he said:— As the rain and the snow come down from heaven and return not there, but fertilize the earth and cause it to bring forth and give seed to the sower and bread for food, so shall the word be that goes forth from My mouth, and it shall not return to Me void, but shall accomplish whatsoever I desire and shall accomplish that for which I shall have sent it. For the rain and the snow do not return to heaven, but accomplish in the earth the will of Him that sends them.
So the word that He shall send through His Christ, Who is Himself the Word and the Message, shall return to Him with great power. For when He shall come and bring it, He shall come down like rain and snow, and through Him all that is sown shall spring up and bear righteous fruit, and the word shall return to His sender; but not in vain shall His going have been, but thus shall He say in the presence of His sender:— Behold, I and the children that the Lord has given Me. And this is the voice through which the dead shall live.
Concerning it our Redeemer testifies, saying:— The hour shall come when even the dead shall hear the voice of the Son of Man and shall come forth from their tombs; as it is written, In the beginning was the voice, that is the Word. Again He said, The Word became a body and dwelt among us. And this is that voice of God which shall sound from on high and raise up all the dead.
Source: Demonstrations (New Advent)