The limit Neville sets on his own teaching, given as doctrine rather than modesty. No one knows the Father except the Son, and anyone to whom the Son chooses to reveal him - so the revelation belongs to the Son to give and not to the teacher to arrange. He can say with certainty that the hearer will be the father; he has no power to tear that curtain from the mind and show him David. When it is torn there is no doubt whatsoever: you are looking at your only begotten son, begotten not by any woman in this world but out of your own being, and he is exactly as the Book of Samuel describes him. Neville reports the after-effect without embarrassment - you are so excited you can think of nothing else and you may bore everyone you meet - and then the sobering half: having seen it you still walk the earth shut out, wearing the garment of flesh, unable to make it actual or share it, until the garment comes off for the last time.