8 “The hour comes, and now is, when the dead shall hear the voice of the Son of God; and they that hear shall live.” From what source shall they live? From life. From what life? From Christ. How do we prove that the source is Christ the life? “I am,” says He, “the way, the truth, and the life.” Do you wish to walk? “I am the way.” Do you wish not to be deceived? “I am the truth.” Would you not die? “I am the life.” This says your Saviour to you: There is not whither you may go but to me; there is not whereby you may go but by me. Therefore this hour is going on now, this act is clearly taking place, and does not at all cease. Men who were dead, rise; they pass over to life; at the voice of the Son of God they live; from Him they live, while persevering in the faith of Him. For the Son has life, whence He has it that they that believe shall live.
Source: Tractates on the Gospel of John (New Advent)