In Blake's Milton the decisive moment when Milton felt compelled to leave Heaven and go to Eternal Death initiated his journey to "Albions land: Which is this earth of vegetation on which now I (Blake) write."
Blake assumed the role of recording the transformation of Milton's "immortal self'" as he experienced events in the world of time and space. His journey was both outward though the natural world and inward through his own psyche.
Milton's psyche was divided as he determined to redeem his "Sixfold Emanation scatter'd thro' the deep In torment!" He becomes a quaternary consisting of his Humanity, his Shadow, his Emanation and his Spectre. Each aspect of his eternal self had work to do in the journey to wholeness.
Blake first dealt with the Shadow which is delusion without substance. It is not error itself but the image of error - without form it cannot be destroyed. Urizen must receive a body before he can be confronted by Milton. Blake and Milton both knew that the reasoning mind tended to dominate the psyche, therefore Blake first tackeled Urizen in order to begin the changes needed in Milton.
Milton's religion was tainted by Puritanism, a strict religion based on rules and punishment. Paradise Lost emphasized the failures of Satan, Eve and Adam to abide by God's dictates. They suffered alienation and penalties for their disobedience.
Blake's Milton postulates that through hearing the Bard's Song in heaven, Milton became aware that his poetic works, his instructional pamplets, his participation in revolution, and his relation with women were based on errors which required correction. His consciousnes of himself was distorted by his inability to discern truth.
Blake attempted to examine Milton's life and work with the aim of separating truth from error in Milton's life and work, for the purpose of building on Milton's experience to enhance his own prophetic calling.
From The Iluminated Blake, by David v Erdman, (Page 236):
"Los shoots his limbs forth 'like the limbs of trees" - and we see that he is almost headless. .. Urizen, nothing but head, peers from the ground and beholds "the immortal Man."
...
Historically the separation of England's head and body is what happened in the "fury premature" of 1649; it was justified by the republican Milton, but the ensuing Civil War did not achieve a resurrected England. In the Bard's Song King Charles "calls upon Milton for atonement."'
Milton, Plate 14,[15], (E 108)
"Then on the verge of Beulah he beheld his own Shadow;
A mournful form double; hermaphroditic: male & female
In one wonderful body. and he enterd into it
In direful pain for the dread shadow, twenty-seven-fold
Reachd to the depths of direst Hell, & thence to Albions land:
Which is this earth of vegetation on which now I write,
The Seven Angels of the Presence wept over Miltons Shadow!"
Milton, Plate 15 [17], (E 109)
"As when a man dreams, he reflects not that his body sleeps,
Else he would wake; so seem'd he entering his Shadow: but
With him the Spirits of the Seven Angels of the Presence
Entering; they gave him still perceptions of his Sleeping Body;
Which now arose and walk'd with them in Eden, as an Eighth
Image Divine tho' darken'd; and tho walking as one walks
In sleep; and the Seven comforted and supported him."
Milton, Plate 17,[19], (E 110)
"In those three females whom his Wives, & those three whom his Daughters
Had represented and containd, that they might be resum'd
By giving up of Selfhood: & they distant view'd his journey
In their eternal spheres, now Human, tho' their Bodies remain clos'd
In the dark Ulro till the Judgment: also Milton knew: they and
Himself was Human, tho' now wandering thro Death's Vale
In conflict with those Female forms, which in blood & jealousy
Surrounded him, dividing & uniting without end or number.
He saw the Cruelties of Ulro, and he wrote them down
In iron tablets: and his Wives & Daughters names were these
Rahab and Tirzah, & Milcah & Malah & Noah & Hoglah,
They sat rangd round him as the rocks of Horeb round the land
Of Canaan: and they wrote in thunder smoke and fire
His dictate; and his body was the Rock Sinai; that body,
Which was on earth born to corruption: & the six Females
Are Hor & Peor & Bashan & Abarim & Lebanon & Hermon
Seven rocky masses terrible in the Desarts of Midian.
But Miltons Human Shadow continu'd journeying above
The rocky masses of The Mundane Shell; in the Lands
Of Edom & Aram & Moab & Midian & Amalek.
The Mundane Shell, is a vast Concave Earth: an immense
Hardend shadow of all things upon our Vegetated Earth
Enlarg'd into dimension & deform'd into indefinite space,
In Twenty-seven Heavens and all their Hells; with Chaos
And Ancient Night; & Purgatory. It is a cavernous Earth
Of labyrinthine intricacy, twenty-seven folds of opakeness
And finishes where the lark mounts; here Milton journeyed
In that Region calld Midian among the Rocks of Horeb
For travellers from Eternity. pass outward to Satans seat,
But travellers to Eternity. pass inward to Golgonooza.
Los the Vehicular terror beheld him, & divine Enitharmon
Call'd all her daughters, Saying. Surely to unloose my bond
Is this Man come! Satan shall be unloosd upon Albion
Los heard in terror Enitharmons words: in fibrous strength
His limbs shot forth like roots of trees against the forward path
Of Miltons journey. Urizen beheld the immortal Man,"