Thus, then, we may understand all things to have been delivered to the Saviour, and, if it be necessary to follow up understanding by explanation, that has been delivered unto Him which He did not previously possess. For He was not man previously, but became man for the sake of saving man. And the Word was not in the beginning flesh, but has been made flesh subsequently, in which Flesh, as the Apostle says, He reconciled the enmity which was against us and destroyed the law of the commandments in ordinances, that He might make the two into one new man, making peace, and reconcile both in one body to the Father. That, however, which the Father has, belongs also to the Son, as also He says in John, 'All things whatsoever the Father has are Mine', expressions which could not be improved. For when He became that which He was not, 'all things were delivered' to Him. But when He desires to declare His unity with the Father, He teaches it without any reserve, saying: 'All things whatsoever the Father has are Mine.' And one cannot but admire the exactness of the language. For He has not said 'all things whatsoever the Father has, He has given to Me,' lest He should appear at one time not to have possessed these things; but 'are Mine.' For these things, being in the Father's power, are equally in that of the Son. But we must in turn examine what things 'the Father has.' For if Creation is meant, the Father had nothing before creation, and proves to have received something additional from Creation; but far be it to think this. For just as He exists before creation, so before creation also He has what He has, which we also believe to belong to the Son. For if the Son is in the Father, then all things that the Father has belong to the Son. So this expression is subversive of the perversity of the heterodox in saying that 'if all things have been delivered to the Son, then the Father has ceased to have power over what is delivered, having appointed the Son in His place. For, in fact, the Father judges none, but has given all judgment to the Son?'. But 'let the mouth of them that speak wickedness be stopped', (for although He has given all judgment to the Son, He is not, therefore, stripped of lordship: nor, because it is said that all things are delivered by the Father to the Son, is He any the less over all), separating as they clearly do the Only-begotten from God, Who is by nature inseparable from Him, even though in their madness they separate Him by their words, not perceiving, the impious men, that the Light can never be separated from the sun, in which it resides by nature. For one must use a poor simile drawn from tangible and familiar objects to put our idea into words, since it is over bold to intrude upon the incomprehensible nature [of God].
§4. The text John 16:15 , shows clearly the essential relation of the Son to the Father.
As then the light from the Sun which illumines the world could never be supposed, by men of sound mind, to do so without the Sun, since the Sun's light is united to the Sun by nature; and as, if the Light were to say: I have received from the Sun the power of illumining all things, and of giving growth and strength to them by the heat that is in me, no one will be mad enough to think that the mention of the Sun is meant to separate him from what is his nature, namely the light; so piety would have us perceive that the Divine Essence of the Word is united by nature to His own Father. For the text before us will put our problem in the clearest possible light, seeing that the Saviour said, 'All things whatsoever the Father has are Mine;' which shows that He is ever with the Father. For 'whatsoever He has' shows that the Father wields the Lordship, while 'are Mine' shows the inseparable union. It is necessary, then, that we should perceive that in the Father reside Everlastingness, Eternity, Immortality. Now these reside in Him not as adventitious attributes, but, as it were, in a well-spring they reside in Him, and in the Son. When then you wish to perceive what relates to the Son, learn what is in the Father, for this is what you must believe to be in the Son. If then the Father is a thing created or made, these qualities belong also to the Son. And if it is permissible to say of the Father 'there was once a time when He was not,' or 'made of nothing,' let these words be applied also to the Son. But if it is impious to ascribe these attributes to the Father, grant that it is impious also to ascribe them to the Son. For what belongs to the Father, belongs to the Son. For he that honours the Son, honours the Father that sent Him, and he that receives the Son, receives the Father with Him, because he that has seen the Son has seen the Father. As then the Father is not a creature, so neither is the Son; and as it is not possible to say of Him 'there was a time when He was not,' nor 'made of nothing,' so it is not proper to say the like of the Son either. But rather, as the Father's attributes are Everlastingness, Immortality, Eternity, and the being no creature, it follows that thus also we must think of the Son. For as it is written, 'As the Father has life in Himself, so gave He to the Son also to have life in Himself.' But He uses the word 'gave' in order to point to the Father who gives. As, again, life is in the Father, so also is it in the Son, so as to show Him to be inseparable and everlasting. For this is why He speaks with exactness, 'whatsoever the Father has,' in order namely that by thus mentioning the Father He may avoid being thought to be the Father Himself. For He does not say 'I am the Father,' but 'whatsoever the Father has.'
§5. The same text further explained.
For His Only-begotten Son might, you Arians, be called 'Father' by His Father, yet not in the sense in which you in your error might perhaps understand it, but (while Son of the Father that begot Him) 'Father of the coming age'. For it is necessary not to leave any of your surmises open to you. Well then, He says by the prophet, 'A Son is born and given to us, whose government is upon his shoulder, and his name shall be called Angel of Great Counsel, mighty God, Ruler, Father of the coming age'. The Only-begotten Son of God, then, is at once Father of the coming age, and mighty God, and Ruler. And it is shown clearly that all things whatsoever the Father has are His, and that as the Father gives life, the Son likewise is able to quicken whom He will. For 'the dead,' He says, 'shall hear the voice of the Son, and shall live', and the will and desire of Father and Son is one, since their nature also is one and indivisible. And the Arians torture themselves to no purpose, from not understanding the saying of our Saviour, 'All things whatsoever the Father has are Mine.' For from this passage at once the delusion of Sabellius can be upset, and it will expose the folly of our modern Jews. For this is why the Only begotten, having life in Himself as the Father has, also knows alone Who the Father is, namely, because He is in the Father and the Father in Him. For He is His Image, and consequently, because He is His Image, all that belongs to the Father is in Him. He is an exact seal, showing in Himself the Father; living Word and true, Power, Wisdom, our Sanctification and Redemption. For 'in Him we both live and move and have our being', and 'no man knows Who is the Father, save the Son, and Who is the Son, save the Father?'.
§6. The Trisagion wrongly explained by Arians. Its true significance.
Source: On Luke 10:22 (Matthew 11:27) (New Advent)