…if, He were a being who was visible by nature, and merely escaped or baffled the view of a frailer creature, but because by the nature of His being it is impossible for Him to be seen. And if you should ask of me what is my opinion regarding the Only-begotten Himself, whether the nature of God, which is naturally invisible, be not visible even to Him, let not such a question appear to you at once to be either absurd or impious, because we shall give you a logical reason. It is one thing to see, and another to know: to see and to be seen is a property of bodies; to know and to be known, an attribute of intellectual being. Whatever, therefore, is a property of bodies, cannot be predicated either of the Father or of the Son; but what belongs to the nature of deity is common to the Father and the Son. Finally, even He Himself, in the Gospel, did not say that no one has seen the Father, save the Son, nor any one the Son, save the Father; but His words are: “No one knoweth the Son, save the Father; nor any one the Father, save the Son.” By which it is clearly shown, that whatever among bodily natures is called seeing and being seen, is termed, between the Father and the Son, a knowing and being known, by means of the power of knowledge, not by the frailness of the sense of sight. Because, then, neither seeing nor being seen can be properly applied to an incorporeal and invisible nature, neither is the Father, in the Gospel, said to be seen by the Son, nor the Son by the Father, but the one is said to be known by the other.
Origen
On First Principles, Book I
Chapter I