This is taught by Scripture and is to be seen by the reason. Scripture teaches that God the Father has never been seen or heard, and cannot be seen or heard either; nor likewise can anything from Him, such as He is in His being and His essence, work upon man. For the Lord says:

No one has seen God, except Him who is with the Father; He has seen the Father. John 6:46.

No one knows the Father, except the Son, and any to whom the Son has wished to reveal Him. Matt. 11:27.

You have never heard the Father's voice, nor have you seen His appearance. John 5:37.

The reason is that He is in the first principles and beginnings of everything, and so is far and away above any level attainable by the human mind. For He is in the first principles and beginnings of the whole of wisdom and the whole of love, and with these man can have no link. Therefore if He should approach a person, or a person should approach Him, he would be consumed and dissolved, like a piece of wood in the focus of a large burning glass, or rather like an image thrown into the sun itself. That is why Moses was told, when he desired to see God, that man cannot see Him and live (Exod. 33:20).

[2] It is evident from the passages just quoted that a link is possible with God the Father through the Lord. These state that it is not the Father, but the only-begotten Son, who is in the Father's bosom and has seen the Father, who has expounded and revealed what is of God and from God. Moreover, it is evident from the following.:

On that day you will know that I am in my Father, and you are in me and I am in you. John 14:20.

I have given them the glory which you gave me, so that they might be one, as we are one; I in them and you in me. John 17:22, 23, 26.

Jesus said, I am the way, truth and life. No one comes to the Father except through me. And then Philip wished to see the Father, but the Lord answered him, He who sees me sees the Father also, and he who knows me knows the Father also. John 14:6, 7ff.

Elsewhere:

He who sees me sees Him who sent me. John 12:45.

Moreover He says that He is the door, and he who enters by Him is saved, and he who climbs up another way is a thief and a robber (John 10:1, 9). He also says that he who does not remain in Him is cast out of doors, and thrown into the fire like a withered branch (John 15:6).

[3] This is because the Lord our Saviour is Jehovah the Father himself in human form; for Jehovah came down and became man, so that He could approach men and men could approach Him, thus establishing a link, and by the link give men salvation and everlasting life. For when God became man, and so man also became God, then by adapting Himself suitably He could approach men, and be linked with them as God-man and Man-god. There are three stages which follow in sequence: adaptation, application and linking. There must be adaptation before there can be application; and there must be adaptation and application together before linking is possible. Adaptation was achieved by God by becoming man. Application by God is constant, in so far as man in turn applies himself; and as this happens, so linking takes place. These three stages follow and proceed in their proper sequence in all details, which become one and come into existence together.