John 16:13

(Hom. lxxviii. 2) In this way then He raised their spirits; for there is nothing for which mankind so long, as the knowledge of the future. He relieves them from all anxiety on this account, by showing that dangers would not fall upon them unawares. Then to show that He could have told them all the truth into which the Holy Spirit would lead them, He adds, He shall glorify Me. (Hom. lxxviii. 2) And because He had said, Ye have one Master, even Christ, (Mat. 23:8) that they might not be prevented by this from admitting the Holy Ghost as well, He adds, For He shall receive of Mine, and shall show it unto you.

What is this that the Lord said of the Holy Spirit, when promising that He would come and teach His disciples all truth, or, guide them into all truth: "For He shall not speak of Himself; but whatsoever He shall hear, that shall He speak"? For this is similar to what He said of Himself, "I can of mine own self do nothing: as I hear, I judge." But when expounding that, we said that it might be taken as referring to His human nature; so that He seemed as the Son to announce beforehand that His own obedience, whereby He became obedient even unto the death of the cross, would have its place also in the judgment, when He shall judge the quick and the dead; for He shall do so for the very reason that He is the Son of man. But when it is said of the Holy Spirit, "For He shall not speak of Himself; but whatsoever He shall hear, that shall He speak," shall we dare to harbor the notion that it was so said in reference to any human nature of His, or the assumption of any creature-form? For it was the Son alone in the Trinity who assumed the form of a servant, a form which in His case was fitted into the unity of His person.

For the fact that the Holy Spirit appeared in bodily form, as a dove, was a sight begun and ended at the time: just as also, when He descended upon the disciples, there were seen upon them cloven tongues as of fire, which also sat upon every one of them. Any one, therefore, who says that the dove was connected with the Holy Spirit in the unity of His person, as that it and Godhead (for the Holy Spirit is God) should go to constitute the one person of the Holy Spirit, is compelled also to affirm the same thing of that fire; and so may understand that he ought to assert neither. For those things in regard to the substance of God, which needed at any time to be represented in some outward way, and so exhibited themselves to men's bodily senses, and then passed away, were formed for the moment by divine power from the subservient creation, and not from the dominant nature itself; which, ever abiding the same, excites into action whatever it pleases; and, itself unchangeable, changes all things else at its pleasure.

You ought to be informed in the first place, and, those of you who can, to understand, and the others, who cannot as yet understand, to believe, that in that substantial essence, which is God, the senses are not, as if through some material structure of a body, distributed in their appropriate places; as, in the mortal flesh of all animals there is in one place sight, in another hearing, in another taste, in another smelling, and over the whole the sense of touch. Far be it from us to believe so in the case of that incorporeal and immutable nature. In it, therefore, hearing and seeing are one and the same thing. But these are not in God's case in different parts of the body. For when He is said to know, all are included: both seeing, and hearing, and smelling, and tasting, and touching; without any alteration of His substance, and without the existence of any material element which is greater in one place and smaller in another: and when there are any such thoughts of God in those even who are old in years, they are the thoughts only of a childish mind.

When it is said of the Holy Spirit, "For He shall not speak of Himself; but whatsoever He shall hear, that shall He speak," so much the more is a simple nature, which is simple in the truest sense, to be either understood or believed, which in its extent and sublimity far surpasses the nature of our minds. For there is mutability in our mind, which comes by learning to the perception of what it was previously ignorant of, and loses by unlearning what it formerly knew; and is deceived by what has a similarity to truth, so as to approve of the false in place of the true, and is hindered by its own obscurity as by a kind of darkness from arriving at the truth. And so that substance is not in the truest sense simple, to which being is not identical with knowing; for it can exist without the possession of knowledge. But it cannot be so with that divine substance, for it is what it has. And on this account it has not knowledge in any such way as that the knowledge whereby it knows should be to it one thing, and the essence whereby it exists another; but both are one.