4 But when He says, “He shall receive of mine, and shall show it unto you,” listen thereto with Catholic ears, and receive it with Catholic minds. For not surely on that account, as certain heretics have imagined, is the Holy Spirit inferior to the Son; as if the Son received from the Father, and the Holy Spirit from the Son, in reference to certain gradations of natures. Far be it from us to believe this, or to say it, and from Christian hearts to think it. In fine, He Himself straightway solved the question, and explained why He said so.
“All things that the Father has are mine: therefore, said I, that He shall take of mine, and shall show it unto you.” What would you more? The Holy Spirit thus receives of the Father, of whom the Son receives; for in this Trinity the Son is born of the Father, and from the Father the Holy Spirit proceeds. He, however, who is born of none, and proceeds from none, is the Father alone. But in what sense it is that the only-begotten Son said, “All things that the Father has are mine” (for it certainly was not in the same sense as when it was said to that son, who was not only begotten, but the elder of two, “You are ever with me; and all that I have is yours),” will have our careful consideration, if the Lord so will, in connection with the passage where the Only-begotten says to the Father, “And all mine are Yours, and Yours are mine;” so that our present discourse may be here brought to a close, as the words that follow require a different opening for their discussion.
Source: Tractates on the Gospel of John (New Advent)