John 10:7

(ut sup.) Our Lord feedeth by plain words, exerciseth by obscure. For when two persons, one godly, the other ungodly, hear the words of the Gospel, and they happen to be such that neither can understand them; one says, What He saith is true and good, but we do not understand it: the other says, It is not worth attending to. The former, in faith, knocks, yea, and, if he continue to knock, it shall be opened unto him. The latter shall hear the words in Isaiah, If ye will not believe, surely ye shall not be established. (Isa. 7:9) (Tr. xlv. 8) Lo, the very door which He had shut up, He openeth; He is the Door: let us enter, and let us enter with joy.

Return then with me to what I was saying, in case it is so to be understood that we may both escape from the question. For I see how I, according to the catholic faith, may escape without tripping or stumbling; whilst thou, on the other hand, shut in on every side, art seeking a way of escape. See by what way thou hast entered. Perhaps thou hast not understood this that I said, See by what way thou hast entered: hear Himself saying, "I am the door." Not without cause, then, art thou seeking how thou mayest get out; and this only thou findest, that thou hast not entered by the door, but fell in over the wall. Therefore raise thyself up from thy fall how thou canst, and enter by the door, that thou mayest go in without stumbling, and go out without straying. Come by Christ, not bringing forward of thy own heart what thou mayest say; but what He shows, that speak.

He most thoroughly knew, being by nature God, and beholding that which lies in the depth, that the Pharisees understood none of His sayings, although accustomed to pride themselves greatly on their learning in the Law, and excessively supercilious in thinking themselves wise. Therefore He gives them a very clear explanation, and winding up as it were the long thread of the argument, He tells them in few words the main scope of the parable.

He says that he is the door of the sheep because he is the principal access to truth for everyone. His doctrine that he has uniquely established calls everyone that is summoned by it. He established laws, as was his prerogative, so that we might …

No one, then, he says, can be saved or return (into heaven) without the Son, and the Son is the Serpent. For as he brought down from above the paternal marks, so again he carries up from thence those marks roused from a dormant condition and rendered paternal characteristics, substantial ones from the unsubstantial Being, transferring them hither from thence. This, he says, is what is spoken: "I am the door." And he transfers (those marks), he says, to those who close the eyelid, as the naphtha drawing the fire in every direction towards itself; nay rather, as the magnet (attracting) the iron and not anything else, or just as the backbone of the sea falcon, the gold and nothing else, or as the chaff is led by the amber. In this manner, he says, is the portrayed, perfect, and con-substantial genus drawn again from the world by the Serpent; nor does he (attract) anything else, as it has been sent down by him. For a proof of this, they adduce the anatomy of the brain, assimilating, from the fact of its immobility, the brain itself to the Father, and the cerebellum to the Son, because of its being moved and being of the form of (the head of) a serpent. And they allege that this (cerebellum), by an ineffable and inscrutable process, attracts through the pineal gland the spiritual and life-giving substance emanating from the vaulted chamber (in which the brain is embedded). And on receiving this, the cerebellum in an ineffable manner imparts the ideas, just as the Son does, to matter; or, in other words, the seeds and the genera of the things produced according to the flesh flow along into the spinal marrow. Employing this exemplar, (the heretics) seem to adroitly introduce their secret mysteries, which are delivered in silence. Now it would be impious for us to declare these; yet it is easy to form an idea of them, by reason of the many statements that have been made.