Didymus the Blind

(ut supr.) He shall not speak of Himself i. e. not without Me, and Mine and the Father’s will: because He is not of Himself, but from the Father and Me. That He exists, and that He speaks, He hath from the Father and Me. I speak the truth; i. e. I inspire as well as speak by Him, since He is the Spirit of Truth. To say and to speak in the Trinity must not be understood according to our usage, but according to the usage of incorporeal natures, and especially the Trinity, which implants Its will in the hearts of believers, and of those who are worthy to hear It. For the Father then to speak, and the Son to hear, is a mode of expressing (significatio est) the identity of their nature, and their agreement. Again, the Holy Spirit, Who is the Spirit of truth, and the Spirit of wisdom, cannot hear from the Son what He does not know, seeing He is the very thing which is produced from the Son, i. e. truth proceeding from truth, Comforter from Comforter, God from God. Lastly, lest any one should separate Him from the will and society of the Father and the Son, it is written, Whatsoever He shall hear, that shall He speak.