Gregory the Great
Catena Aurea · Johannesevangelium 14
Judas saith unto him, not Iscariot, Lord, how is it that thou wilt manifest thyself unto us, and not unto the world? Jesus answered and said unto him, If a man love me, he will keep my words: and my Father will love him, and we will come unto him, and make our abode with him. He that loveth me not keepeth not my sayings: and the word which ye hear is not mine, but the Father’s which sent me. These things have I spoken unto you, being yet present with you. But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you. Peace I leave with you, my peace I give unto you: not as the world giveth, give I unto you.
(Hom. xxx.) Unless the Spirit be present to the mind of the hearer, the word of the teacher is vain. Let none then attribute to the human teacher, the understanding which follows in consequence of his teaching: for unless there be a teacher within, the tongue of the teacher outside will labour in vain. Nay even the Maker Himself does not speak for the instruction of man, unless the Spirit by His unction speaks at the same time.