Texts Explained; Secondly, Psalm 45:7, 8.--> Whether the words 'therefore,' 'anointed,' etc., imply that the Word has been rewarded. Argued against first from the word 'fellows' or 'partakers.' He is anointed with the Spirit in His manhood to sanctify human nature. Therefore the Spirit descended on Him in Jordan, when in the flesh. And He is said to sanctify Himself for us, and give us the gloryHe has received. The word 'wherefore' implies His divinity. 'You have loved righteousness,' etc., do not imply trial or choice
46 Such an explanation of the Apostle's words confutes the irreligious men; and what the sacred poet says admits also the same orthodox sense, which they misinterpret, but which in the Psalmist is manifestly religious. He says then, 'Your throne, O God, is for ever and ever; a sceptre of righteousness is the sceptre of Your Kingdom. You have loved righteousness, and hated iniquity, therefore God, even Your God, has anointed You with the oil of gladness above Your fellows. ' Behold, O you Arians, and acknowledge even hence the truth. The Singer speaks of us all as 'fellows' or 'partakers' of the Lord: but were He one of things which come out of nothing and of things originate, He Himself had been one of those who partake. But, since he hymned Him as the eternal God, saying, 'Your throne, O God, is for ever and ever,' and has declared that all other things partake of Him, what conclusion must we draw, but that He is distinct from originated things, and He only the Father's veritable Word, Radiance, and Wisdom, which all things originate partake, being sanctified by Him in the Spirit? And therefore He is here 'anointed,' not that He may become God, for He was so even before; nor that He may become King, for He had the Kingdom eternally, existing as God's Image, as the sacred Oracle shows; but in our behalf is this written, as before. For the Israelitish kings, upon their being anointed, then became kings, not being so before, as David, as Hezekiah, as Josiah, and the rest; but the Saviour on the contrary, being God, and ever ruling in the Father's Kingdom, and being Himself He that supplies the Holy Ghost, nevertheless is here said to be anointed, that, as before, being said as man to be anointed with the Spirit, He might provide for us men, not only exaltation and resurrection, but the indwelling and intimacy of the Spirit. And signifying this the Lord Himself has said by His own mouth in the Gospel according to John, 'I have sent them into the world, and for their sakes do I sanctify Myself, that they may be sanctified in the truth. ' In saying this He has shown that He is not the sanctified, but the Sanctifier; for He is not sanctified by other, but Himself sanctifies Himself, that we may be sanctified in the truth. He who sanctifies Himself is Lord of sanctification. How then does this take place? What does He mean but this? 'I, being the Father's Word, I give to Myself, when becoming man, the Spirit; and Myself, become man, do I sanctify in Him, that henceforth in Me, who am Truth (for “Your Word is Truth”), all may be sanctified.'
47. If then for our sake He sanctifies Himself, and does this when He has become man, it is very plain that the Spirit's descent on Him in Jordan was a descent upon us, because of His bearing our body. And it did not take place for promotion to the Word, but again for our sanctification, that we might share His anointing, and of us it might be said, 'Do you not know that you are God's Temple, and the Spirit of God dwells in you?' For when the Lord, as man, was washed in Jordan, it was we who were washed in Him and by Him. And when He received the Spirit, we it was who by Him were made recipients of It. And moreover for this reason, not as Aaron or David or the rest, was He anointed with oil, but in another way above all His fellows, 'with the oil of gladness,' which He Himself interprets to be the Spirit, saying by the Prophet, 'The Spirit of the Lord is upon Me, because the Lord has anointed Me;' as also the Apostle has said, 'How God anointed Him with the Holy Ghost. ' When then were these things spoken of Him but when He came in the flesh and was baptized in Jordan, and the Spirit descended on Him? And indeed the Lord Himself said, 'The Spirit shall take of Mine;' and 'I will send Him;' and to His disciples, 'Receive the Holy Ghost. ' And notwithstanding, He who, as the Word and Radiance of the Father, gives to others, now is said to be sanctified, because now He has become man, and the Body that is sanctified is His. From Him then we have begun to receive the unction and the seal, John saying, 'And you have an unction from the Holy One;' and the Apostle, 'And you were sealed with the Holy Spirit of promise. ' Therefore because of us and for us are these words. What advance then of promotion, and reward of virtue or generally of conduct, is proved from this in our Lord's instance? For if He was not God, and then had become God, if not being King He was preferred to the Kingdom, your reasoning would have had some faint plausibility. But if He is God and the throne of His kingdom is everlasting, in what way could God advance? Or what was there wanting to Him who was sitting on His Father's throne? And if, as the Lord Himself has said, the Spirit is His, and takes of His, and He sends It, it is not the Word, considered as the Word and Wisdom, who is anointed with the Spirit which He Himself gives, but the flesh assumed by Him which is anointed in Him and by Him; that the sanctification coming to the Lord as man, may come to all men from Him. For not of Itself, says He, does the Spirit speak, but the Word is He who gives It to the worthy. For this is like the passage considered above; for as the Apostle has written, 'Who existing in form of God thought it not a prize to be equal with God, but emptied Himself, and took a servant's form,' so David celebrates the Lord, as the everlasting God and King, but sent to us and assuming our body which is mortal. For this is his meaning in the Psalm, 'All your garments smell of myrrh, aloes, and cassia;' and it is represented by Nicodemus and by Mary's company, when the one came bringing 'a mixture of myrrh and aloes, about an hundred pounds weight;' and the others 'the spices which they had prepared' for the burial of the Lord's body.
Source: Four Discourses Against the Arians (New Advent)