1 We have heard, brethren, while the Gospel was read, the Lord saying: “If you love me, keep my commandments: and I will ask the Father, and He shall give you another Comforter [Paraclete], that He may abide with you for ever; [even] the Spirit of truth; whom the world cannot receive, because it sees Him not, neither knows Him: but you shall know Him; for He shall dwell with you, and shall be in you.” There are many points which might form the subject of inquiry in these few words of the Lord; but it were too much for us either to search into all that is here for the searching, or to find out all that we here search for.
Nevertheless, as far as the Lord is pleased to grant us the power, and in proportion to our capacity and yours, attend to what we ought to say and you to hear, and receive, beloved, what we on our part are able to give, and apply to Him for that wherein we fail. It is the Spirit, the Comforter, that Christ has promised to His apostles; but let us notice the way in which He gave the promise. “If you love me,” He says, “keep my commandments: and I will ask the Father, and He shall give you another Comforter, that He may abide with you for ever: [even] the Spirit of truth.”
We have here, at all events, the Holy Spirit in the Trinity, whom the catholic faith acknowledges to be consubstantial and co-eternal with Father and Son: He it is of whom the apostle says, “The love of God is shed abroad in our hearts by the Holy Spirit, who is given unto us.” How, then, does the Lord say, “If you love me, keep my commandments: and I will ask the Father, and He shall give you another Comforter;” when He says so of the Holy Spirit, without [having] whom we can neither love God nor keep His commandments?
How can we love so as to receive Him, without whom we cannot love at all? Or how shall we keep the commandments so as to receive Him, without whom we have no power to keep them? Or can it be that the love wherewith we love Christ has a prior place within us, so that, by thus loving Christ and keeping His commandments, we become worthy of receiving the Holy Spirit, in order that the love, not of Christ, which had already preceded, but of God the Father, may be shed abroad in our hearts by the Holy Spirit, who is given unto us?
Such a thought is altogether wrong. For he who believes that he loves the Son, and loves not the Father, certainly loves not the Son, but some figment of his own imagination. And besides, this is the apostolic declaration, “No one says, Lord Jesus, but in the Holy Spirit:” and who is it that calls Him Lord Jesus but he that loves Him, if he so call Him in the way the apostle intended to be understood? For many call Him so with their lips, but deny Him in their hearts and works; just as He says of such, “For they profess that they know God, but in works they deny Him.” If it is by works He is denied, it is doubtless also by works that His name is truly invoked.
“No one,” therefore, “says, Lord Jesus,” in mind, in word, in deed, with the heart, the lips, the labor of the hands—no one says, Lord Jesus, but in the Holy Spirit; and no one calls Him so but he that loves. And accordingly the apostles were already calling Him Lord Jesus: and if they called Him so, in no way that implied a feigned utterance, with the mouth confessing, in heart and works denying Him; if they called Him so in all truthfulness of soul, there can be no doubt they loved. And how, then, did they love, but in the Holy Spirit? And yet they are commanded to love Him and keep His commandments, previous and in order to their receiving the Holy Spirit: and yet, without having that Spirit, they certainly could not love Him and keep His commandments.
Source: Tractates on the Gospel of John (New Advent)