14 He shall glorify me; because he shall receive of mine, and shall shew it to you.
Chrysostom: Because He had said, Ye have one Master, even Christ [Matt 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 shew it to you.
15 All things whatsoever the Father hath, are mine. Therefore I said, that he shall receive of mine, and shew it to you.
Didymus: That which the Father hath according to His substance, i.e. His eternity, immutability, goodness, it is this which the Son hath also.
To receive must be taken here in a sense agreeable to the Divine Nature. As the Son in giving is not deprived of what He gives, nor imparts to others with any loss of His own, so too the Holy Ghost does not receive what before He had not; for if He received what before He had not, the gift being transferred to another, the giver would be thereby a loser. We must understand then that the Holy Ghost receives from the Son that which belonged to His nature, and that there are not two substances implied, one giving and the other receiving, but one substance only. In like manner the Son too is said to receive from the Father that wherein He Himself subsists. For neither is the Son any thing but what is given Him by the Father, nor the Holy Ghost any substance but that which is given Him by the Son.
Augustine: It is not true, as some heretics have thought, that because the Son receives from the Father, the Holy Ghost from the Son, as if by gradation, that therefore the Holy Ghost is inferior to the Son. He Himself solves this difficulty, and explains His own words: All things that the Father hath are Mine.
Hilary: Nor does it matter from whom the thing is received; since that which is given by the Father is counted also as given by the Son.
Scripture from the Douay-Rheims Bible. Commentary from St. Thomas Aquinas, Catena Aurea, Vol. IV (London: Rivington, 1845).