John 12:29

(Tr. lii. 4) I have glorified it, i. e. before I made the world; and will glorify it again, i. e. when Thou shalt rise from the dead. Or, I have glorified it, when Thou wast born of a Virgin, didst work miracles, wast made manifest by the Holy Ghost descending in the shape of a dove; and will glorify it again, when Thou shalt rise from the dead, and, as God, be exalted above the heavens, and Thy glory above all the earth. The people therefore that stood by and heard it, said that it thundered.

"Then came there a voice from heaven, [saying], I have both glorified it, and will glorify it again." "I have both glorified it," before I created the world, "and I will glorify it again," when He shall rise from the dead and ascend into heaven. It may also be otherwise understood. "I have both glorified it," when He was born of the Virgin, when He exercised miraculous powers; when the Magi, guided by a star in the heavens, bowed in adoration before Him; when He was recognized by saints filled with the Holy Spirit; when He was openly proclaimed by the descent of the Spirit in the form of a dove, and pointed out by the voice that sounded from heaven; when He was transfigured on the mount; when He wrought many miracles, cured and cleansed multitudes, fed so vast a number with a very few loaves, commanded the winds and the waves, and raised the dead; "and I will glorify it again;" when He shall rise from the dead; when death shall have no longer dominion over Him; and when He shall be exalted over the heavens as God, and His glory over all the earth. "The people therefore that stood by, and heard it, said that it thundered: others said, An angel spake to Him. Jesus answered and said, This voice came not because of me, but for your sakes." He thereby showed that the voice made no intimation to Him of what He already knew, but to those who needed the information. And just as that voice was uttered by God, not on His account, but on that of others, so His soul was troubled, not on His own account, but voluntarily for the sake of others.

(Moral. xxviii.) When God speaks audibly, as He does here, but no visible appearance is seen, He speaks through the medium of a rational creature: i. e. by the voice of an Angel.