St. Cyril of Jerusalem
“The Angels see God not as He is, but as far as they themselves are capable. For it is Jesus Himself who says, Not that any man has seen the Father, save He which is of God, He has seen the Father. John 6:46 The Angels therefore behold as much as they can bear, and Archangels as much as they are able; and Thrones and Dominions more than the former, but yet less than His worthiness: for with the Son the Holy Ghost alone can rightly behold Him: for He searches all things, and knows even the deep things of God 1 Corinthians 2:10: as indeed the Only-begotten Son also, with the Holy Ghost, knows the Father fully… Since Angels then are ignorant (for to each according to his own capacity does the Only-begotten reveal Him through the Holy Ghost, as we have said), let no man be ashamed to confess his ignorance.”
Source: St. Cyril of Jerusalem, Catechetical Lectures