They understood not that he spoke to them of the Father.
All Commentaries on John 8:27 Go To John 8
Cyril of Alexandria
AD 444
The Spirit-clad is astonishment-stricken at the senselessness of the Jews, and with great reason: for what more without understanding than such, who, when much discourse and often had been made to them concerning God the Father, conceive not of Him a whit when they hear our Saviour saying, But He That sent Me is True? What then is the plea, and why the blessed Evangelist says that the Jews knew not that Christ in these words signified God the Father to them, we must needs say. For since the Saviour said to them, If ye had known Me, ye should have known My Father also, in order that in this too He may be found saying what was true, the Evangelist brings in those who know not the Son, as ignorant of the Father too. For the Son is (so to speak) a Door and Gate unto the knowledge of the Father, wherefore He also said, No man cometh unto the Father but by Me. For the mind darting up from Image to Archetype imageth the other from what is before it. It was necessary therefore to shew that the Jews had no conception of the Father, since they would not be led, upward mounting from knowledge of the Son to conception of the Father. Wherefore does the Evangelist clearly shew that when Christ says, He That sent Me is True, they knew not that He spake to them of the Father.
