Augustine of Hippo
Catena Aurea · Johannesevangelium 16
But now I go my way to him that sent me; and none of you asketh me, Whither goest thou? But because I have said these tilings unto you, sorrow hath filled your heart. Nevertheless I tell you the truth; It is expedient for you that I go away: for if I go not away, the Comforter will not come unto you; but if I depart, I will send him unto you. And when he is come, he will reprove the world of sin, and of righteousness, and of judgment: Of sin, because they believe not on me; Of righteousness, because I go to my Father, and ye see me no more; Of judgment, because the prince of this world is judged.
(i. de Trin. c. 9.) This He says not on account of any inequality between the Word of God and the Holy Ghost, but because the presence of the Son of man amongst them would impede the coming of the latter. For the Holy Ghost did not humble Himself as did the Son, by taking upon Him the form of a servant. It was necessary therefore that the form of the servant should he removed from their eyes; for so long as they looked upon that, they thought that Christ was no more than what they saw Him to be. So it follows: But if I depart, I will send Him unto you.