Ambrose of Milan
Catena Aurea · Lukasevangelium 9
And it came to pass about an eight days after these sayings, he took Peter and John and James, and went up into a mountain to pray. And as he prayed, the fashion of his countenance was altered, and his raiment was white and glistering. And, behold, there talked with him two men, which were Moses and Elias: Who appeared in glory, and spake of his decease which he should accomplish at Jerusalem.
Now in a mystical manner, after the words above said, is exhibited the transfiguration of Christ, since he who hears the words of Christ, and believes, shall see the glory of His resurrection. For, on the eighth day the resurrection took place. Hence also several Psalms are written, ‘for the eighth,’ (pro octava.)or perhaps it was that He might make manifest what He had said, that he who for the word of God shall lose his own life, shall save it, seeing that He will make good His promises at the resurrection.