John Milton draws on the Reformed divines in his A Treatise on Christian Doctrine. I am not familiar with Reformed theology, but I do know that he models his treatise off of two divines. If I recall correctly, the classic reformed approach to God is that God is Pure Being; that is, God cannot interact with His creation except through His decrees. For Milton, the essence of God is “most simple” and “can admit no compound quality” (Milton 19). God is perfect unity, and therefore there can be no plurality in the Godhead, according to Milton. The name God, proper, is only rightly applied to the Father, and He is completely self-existent. God can only interact with created beings through his decrees.
His internal efficiency is the decrees that are “purposed in himself” (Eph. 1:9). His external efficiency is the enactment of the decrees in time. Milton writes that the first and most important of the special decrees is the generation of the Son. Generation means for Milton that the Son is of God, that is, of the substance of the Father. The Son “is the image of the invisible God, the firstborn of every creature” (Col. 1:15). The Father bestowed upon him as much as He pleased, and thus the Son is the “express image of his person” (Heb. 1:3). However, the Son is not God, proper. Milton does not divide the Godhead but rather proclaims that the Son is not one with the Father. For him, the Godhead is inseparable from the Father; it is His ens. The Son is generated from the substance of God by an act of Will. The Son then rests in the bosom of the Father, which Milton sees as analogous to the beloved disciple resting his head upon Jesus’ breast.
For Milton, there can be no real unity in a Trinity of persons. Milton, following his theological predecessors argues God from the essence of God. His opponents argue, according to him, that if God has an infinite essence, then there can be plurality in the Godhead. Milton points out, correctly, that then there is no reason for there to be only three persons; in fact, there should be an infinite amount of persons in an infinite essence.
Therefore, Milton concludes, that the essence of God, being most simple Spirit, can only contain one person. Milton’s understand of hypostasis is that which “can be nothing else but that most perfect essence by which God subsists by himself, in himself, and through himself.” It “denotes not the ens itself, but the essence of the ens in the abstract” (19). Milton equates essence and hypostasis. The substance of God is that which is shared with the Son. The Father generates the Son out of His own substance in time, and the Son is thus a substantial essence. Another way of expressing this concept is that the Son existed from all eternity in the mind of God (internal efficiency), and then the Father generated him in time (external efficiency) from His own divine substance according to his special decree, which he had “purposed in himself.” The Son is divine insofar as he is of the divine substance, but the Son is not coeval or equal with the Father.
I think that Milton’s main problem is his focus on the unity and simplicity of God. He inherited this teaching from the Reformed and the Scholastics before them (someone check me on this point). In Orthodoxy, as I understand it, we approach God from a relational standpoint. It has been revealed that God exists in three persons, and yet God must be one. Therefore God is three hypostases sharing one ousia. God is love, and the Trinity exist in a perfect communion of love. This perfect communion is what allows the three persons to share one essence. The Son proceeds from the Father in the Spirit from all eternity. The Spirit proceeds from the Father and dwells in the Son from all eternity.
Milton writes of the communion of love, but this communion is impersonal. The essence of God is unknown to the Son. The Son knows Him through the honors, power, glory, etc.. bestowed upon him by the Father. It seems to me that Milton’s express individualism and his Calvinist roots may have prevented him from conceiving any real unity in the Trinity. I need to much more research in this topic before coming to any real conclusions. I appreciate any comments.
The Authorized (King James) Version, Cambridge UP, Bible Gateway, https://www.biblegateway.com/versions/Authorized-King-James-Version-AKJV-Bible/#booklist
Milton, John. A Treatise on Christian Doctrine: Compiled from the Holy Scriptures Alone, translated by Charles R. Sumner, Cambridge UP, 1825. Memphis: General Books, 2012, Print.