VISIONARY

Kathleen Raine's Blake and Tradition, published in 1968, represented a breakthrough is connecting Blake's thought to the long tradition of esoteric literature. Following the thread of Blake's sources Raine demonstrates how Blake "always responded when reading any abstract work" by creating images with a "concrete visual quality." (Page 221)
 
On page 228 we read: "Again we find Blake's most visionary, most living figure of Los, his atributes and his operations, deeply rooted in a traditional metaphysical theme. Blake's imagination was at all times ready to be kindled by such themes, often in themselves abstract and recondite; and from such germinal ideas we can follow the growth and ramifications of his myths. For Blake no idea seemed to fully exist until it found expression in being, and being in action. For him there were no abstractions; every abstraction he saw (and personified in the figure of Urizen) as a mode of being. 
...
Thus Blake, in the myth of Los creating the sun of nature, re-creates Swedenborg's doctrine of 'influx'. Spiritual light and fire descend from the spiritual world to be molded by Los into the orb of the natural  sun: 

British Museum

Song of Los
Plate 8, Copy A 

4: And first from those infinite fires
The light that flow'd down on the winds
lie siez'd; beating incessant, condensing
The subtil particles in an Orb.                    

5: Roaring indignant the bright sparks
Endur'd the vast Hammer; but unwearied
Los beat on the Anvil; till glorious
An immense Orb of fire be fram'd

6: Oft he quench'd it beneath in the Deeps        
Then surveyd the all bright mass. Again
Siezing fires from the terrific Orbs
He heated the round Globe, then beat[,]
While roaring his Furnaces endur'd
The chaind Orb in their infinite wombs     

7: Nine ages completed their circles
When Los heated the glowing mass, casting
It down into the Deeps: the Deeps fled
Away in redounding smoke; the Sun
Stood self-balanc'd. And Los smild with joy.        
He the vast Spine of Urizen siez'd
And bound down to the glowing illusion

8: But no light, for the Deep fled away
On all sides, and left an unform'd
Dark vacuity:"
Book of Los, Plate 5, (E 94)