Theophylact of Ohrid — as excerpted in the Catena Aurea on John 8:19-20

“Let the Arian blush: for if, as he says, the Son be a creature, how does it follow that he who knows the creature, knows God? For not even by knowing the substance of Angels, does one know the Divine Substance? Forasmuch therefore as he who knows the Son, knows the Father, it is certain that the Son is consubstantial with the Father.”