Heracleon, in his discussion on John and the Prophets, infers that because the Saviour was the Word, and John the voice, therefore the whole of the prophetic order was only sound. To which we reply, that, if the trumpet gives an uncertain sound, who shall prepare himself for the battle? If the voice of prophecy is nothing but sound, why does the Saviour send us to it, saying, Search the Scriptures? (John 5:39) But John calls himself the voice, not that crieth, but of one that crieth in the wilderness; viz. of Him Who stood and cried, If any man thirst, let him come unto Me and drink. (John 7:37) He cries, in order that those at a distance may hear him, and understand from the loudness of the sound, the vastness of the thing spoken of.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: in Joan. tom. vi. c. 12