The Father is manifested by the voice, only as producing the voice or speaking by it. And since it is proper to the Father to produce the Word–that is, to utter or to speak–therefore was it most becoming that the Father should be manifested by a voice, because the voice designates the word. Wherefore the very voice to which the Father gave utterance bore witness to the Sonship of the Word. And just as the form of the dove, in which the Holy Ghost was made manifest, is not the Nature of the Holy Ghost, nor is the form of man in which the Son Himself was manifested, the very Nature of the Son of God, so neither does the voice belong to the Nature of the Word or of the Father who spoke. Hence (John 5:37) our Lord says: “Neither have you heard His,” i.e. the Father’s, “voice at any time, nor seen His shape.” By which words, as Chrysostom says (Hom. xl in Joan.), “He gradually leads them to the knowledge of the philosophical truth, and shows them that God has neither voice nor shape, but is above all such forms and utterances.” And just as the whole Trinity made both the dove and the human nature assumed by Christ, so also they formed the voice: yet the Father alone as speaking is manifested by the voice, just as the Son alone assumed human nature, and the Holy Ghost alone is manifested in the dove, as Augustine [Fulgentius, De Fide ad Petrum] makes evident.