ALBION'S REACTOR

There is a passage in Jerusalem in we are introduced to Albion's Reactor without any preparation for his introduction. The passage is spoken by the Voice Divine, a term which is used only once in Blake's poetry. Blake uses this voice to speak of man's inability to recognize what is happening because of the limitations of his perspective.

Wikimedia Commons
Jerusalem
Plate 26, Copy A
British Museum

But the Divine Voice knows the plan that was envisioned for mankind and how it was subverted by one aspect withdrawing from the unity. Because mankind is within creation he is unable to see the whole picture or recognize the force which is acting against the reunification of the Divine Humanity. Although the Reactor is not identified by the Divine Voice, we know that one of his names is Satan. He acts against: against receiving the Divine Vision; against reconciling the contraries; against enjoying the liberty which flows from exercising the Divine Arts of Imagination.

Jerusalem, Plate 77, (E231)
"I know of no other
Christianity and of no other Gospel than the liberty both of body
& mind to exercise the Divine Arts of Imagination." 

 Jerusalem, Plate 43, (E 191)
"And thus the Voice Divine went forth upon the rocks of Albion    

I elected Albion for my glory; I gave to him the Nations,
Of the whole Earth. he was the Angel of my Presence: and all
The Sons of God were Albions Sons: and Jerusalem was my joy.
The Reactor hath hid himself thro envy. I behold him.
But you cannot behold him till he be reveald in his System       
Albions Reactor must have a Place prepard: Albion must Sleep
The Sleep of Death, till the Man of Sin & Repentance be reveald.
Hidden in Albions Forests he lurks: he admits of no Reply
From Albion: but hath founded his Reaction into a Law
Of Action, for Obedience to destroy the Contraries of Man[.]     
He hath compelld Albion to become a Punisher & hath possessd
Himself of Albions Forests & Wilds! and Jerusalem is taken!
The City of the Woods in the Forest of Ephratah is taken!
London is a stone of her ruins; Oxford is the dust of her walls!
Sussex & Kent are her scatterd garments: Ireland her holy place! 
And the murderd bodies of her little ones are Scotland and Wales
The Cities of the Nations are the smoke of her consummation
The Nations are her dust! ground by the chariot wheels
Of her lordly conquerors, her palaces levelld with the dust
I come that I may find a way for my banished ones to return      
Fear not O little Flock I come! Albion shall rise again.

So saying, the mild Sun inclosd the Human Family."

Minna Doskow, in William Blake's Jerusalem, gives this insight into Satan as an "erroneous cognitive concept or 'self-delusion'":

"The Divine Voice also supplies the imaginative view of Albion's separation from his Spectre Satan. First, he differentiates Satan's negativity from Albion's sleep, exemplifying the difference between a state and an individual within that state, and second, he shows how Albion's malfunctioning mind produces Satan, who absorbs and dominates him, exemplifying the difference between the creation and its creator. As pure negativity, Satan is the 'reactor' who can only oppose and deny like the Spector of Albion's sons in chapter 1. He also tries to destroy what is positive and grounds 'his Reaction into a law/Of Action, for Obedience to destroy the Contraries of Man'. As negativity, Satan lacks independent concrete existence, so he establishes Albion's historical institutionalized religion in order to achieve such existence...Satan, however, unknowingly serves eternal purposes in his actions (as Los's Spectre does too), for negativity must first become concrete in order to be exposed and abolished. Satan must 'be revealed in his system', which is Albion's religion with its codes and laws before exiled humanity can return to its divinity...Falsehood must be embodied before it can be recognized as error and corrected. This is the constant imaginative truth which unifies all of existence, true of religious as well as rational error."