IMMORTAL LINES

Kathleen Raine's biography titled William Blake was published in 1970, two years after her masterwork, Blake and Tradition, which exhaustively connects Blake's thought with sources within the perennial philosophy. On Page 109 of the biography, Raine begins her exploration of the significance of line to Blake:  

"Line was, for Blake, above all an expression of energy. Every solid form can be seen as the imprint and product of a flow of energy, and it is certain that Blake saw line as energy, as the signature of life."

She continues with this quote from Blake's Exhibition and Catalogue of 1809 (E 550):

"  The great and golden rule of art, as well as of life, is
this: That the more distinct, sharp, [P 64] and wirey the
bounding line, the more perfect the work of art; and the less
keen and sharp, the greater is the evidence of weak imitation,
plagiarism, and bungling.  Great inventors, in all ages, knew
this: Protogenes and Apelles knew each other by this line.
Rafael and Michael Angelo, and Albert Durer, are known by this
and this alone.  The want of this determinate and bounding form
evidences the want of idea in the artist's mind, and the  
pretence of the plagiary in all its branches.  How do we 
distinguish the oak from the beech, the horse from the ox, but 
by the bounding outline? How do we distinguish one face or 
countenance from another, but by the bounding line and its 
infinite inflexions and movements? What is it that builds a house 
and plants a garden, but the definite and determinate? What is it 
that distinguishes honesty from knavery, but the hard and wirey 
line of rectitude and certainty [P 65] in the actions and 
intentions.  Leave out this l[i]ne and you leave out life itself; 
all is chaos again, and the line of the almighty must be drawn 
out upon it before man or beast can exist.

British Museum 
Young's Night Thoughts

Raine states on page 111:
"...For Blake , volume and weight belonged to the mechanistic concept of a natural world subject to the quantitative 'laws of nature' as these operate in time and space; the universe of 'Bacon, Newton and Locke', of the 'Satanic mills' of natural causality - to all that he himself opposed with all the energy of his prophetic mission. Against the mechanistic view of nature, product of the rational mind of Urizen, Blake proclaimed life. Life is non-spatial and non-temporal; gravity does not weigh it down, nor bulk contain it. There are, for Blake's human figures, essentially two conditions - the unconfined freedom of unimpeded energy; and the constricted, fettered, weighted and cramped state of the prisoners of Urizen's universe of mechanized nature. Michelangelo's prisoners, struggling from their rocky confinement, would have signified, for Blake, life freeing itself from the oppression of matter, like the figure of Earth in his own Gates of Paradise."    

In the Four Zoas we find this passage in which giving life and drawing a line are equated. The Spectres of the Dead are embodied as the living through the process of drawing the line. Los drew the line; Enitharmon breathed forth upon the wind. Blake was giving life or body to his images through applying his pen to paper or his graver to copper.   

Four Zoas, Night VII, Page 98, (E 370) 
"So Enitharmon spoke & Los his hands divine inspired began 
To modulate his fires studious the loud roaring flames
He vanquishd with the strength of Art bending their iron points
And drawing them forth delighted upon the winds of Golgonooza 
>From out the ranks of Urizens war & from the fiery lake
Of Orc bending down as the binder of the Sheaves follows   
The reaper in both arms embracing the furious raging flames
Los drew them forth out of the deeps planting his right foot firm
Upon the Iron crag of Urizen thence springing up aloft
Into the heavens of Enitharmon in a mighty circle

And first he drew a line upon the walls of shining heaven    
And Enitharmon tincturd it with beams of blushing love

It remaind permanent a lovely form inspird divinely human
Dividing into just proportions Los unwearied labourd
The immortal lines upon the heavens till with sighs of love
Sweet Enitharmon mild Entrancd breathd forth upon the wind   
The spectrous dead Weeping the Spectres viewd the immortal works
Of Los Assimilating to those forms Embodied & Lovely
In youth & beauty in the arms of Enitharmon mild reposing"

Blake amplifies this concept on the Laocoon Engraving (E 273):

"The Eternal Body of Man is The IMAGINATION.
          God himself  |
that is                |[Yeshua] JESUS We are his Members
        The Divine Body|

It manifests itself in his Works of Art (In Eternity All is
     Vision)"