37. 'And heard behind me a great voice as of a trumpet' signifies a manifest perception of Divine Truth revealed out of heaven. 'A great voice', when it is heard out of heaven signifies Divine Truth, about which [something] follows. It was heard 'as of a trumpet' because when Divine Truth is descending out of heaven it is sometimes so heard by angels of the lowest heaven, and is then manifestly perceived. It is in consequence of this that by 'a voice as of a trumpet' manifest perception is signified. Something further about the signification of a trumpet will be seen below (n. 397, 519). That 'a great voice', when it is heard out of heaven, signifies Divine Truth is plain from these passages:-
The voice of Jehovah upon the waters, the voice of Jehovah in vigour, the voice of Jehovah with honour, the voice of Jehovah breaking the cedars, the voice of Jehovah falling as a flame of fire, the voice of Jehovah makes the wilderness to tremble, the voice of Jehovah makes the hinds to bring forth Ps. xxix 3-9.
Sing psalms to the Lord, O kingdoms of the earth, behold He will give in His voice a voice of strength Ps. lxviii 32, 33 [H.B. 33, 34].
Jehovah uttered His voice in the presence of [His] army, for beyond number it does His Word Joel ii 11.
Jehovah will give forth His voice from Jerusalem Joel iii 16 [H.B. iv 16].
And since 'voice' signifies the Divine Truth [coming] out of the Lord, therefore the Lord said that:-
The sheep hear His voice; they know His voice; I also have other sheep which I ought to bring, and they shall hear My voice. My sheep hear My voice, and I know them, and they follow Me John x 3, 4, 16, 27.
And elsewhere:-
The hour is coming when the dead shall hear the voice of the Son of Man, and they who hear shall live John v 25.
'Voice' here is the Divine Truth of the Lord out of His Word.