John 8:19

Where is thy Father? They knew well enough by other discourses, that he had called and declared God to be his Father; but they had a mind to make him own it again, that they might accuse him as guilty of blasphemy. --- Neither me do you know, nor my Father: you will not own me to have been always his Son, nor him to have been always my Father, but did you know me to be his Son, always proceeding from him, you would know my Father also, and know him as my Father from all eternity. (Witham) --- As in common conversation we often say, "when you have seen one, you have seen the other;" when two persons or things seem perfectly alike as to outward appearances, so here Christ says, If you did know me, you would know my Father also: not that the Father is the Son, or the Son the Father, but because the Father is like the Son. (St. Augustine) --- Here might the Arians, and all who maintain that Christ is a mere creature, blush; for if he were a creature, how can any one who knows him likewise know God? Therefore is Christ consubstantial with the Father, for he who know the Son, knows the Father also. (Theophylactus)