Urizen

Urizen is the primary of the four zoas, standing for reason.  Blake feels that  anyone under Urizen's dominion is restricted by his limitations.

The word strongly suggests reason, the primary quality of Urizen. Blake felt that the hegemony of rational thinking since The Enlightenment had had a stultifying and destructive influence on the British culture. He chose Bacon, Newton and Locke to epitomize that destructive influence. He chose Urizen to exemplify it in his myth.
At the final consummation Blake rehabilitated Bacon, Newton and Locke. They appeared counterbalancing Blake's three great poets.

The Druid Spectre was Annihilate loud thundring rejoicing terrific vanishing J98.7; E257| 

Fourfold Annihilation & at the clangor of the Arrows of Intellect J98.8; E257| The 

innumerable Chariots of the Almighty appeard in Heaven J98.9; E257| And Bacon & Newton & Locke, & Milton & Shakspear & Chaucer (Jerusalem 98: 6-9 [257])
 
In Night II of The Four Zoas Urizen lost his faith and in vision saw the world collapsing into darkness:
FZ2: 23:9-24.8; (314)
Urizen rose from the bright Feast like a star thro' the evening sky.
First he beheld the body of Man pale, cold; the horrors of death
Beneath his feet shot thro' him as he stood in the Human Brain,
Pale he beheld futurity; pale he beheld the Abyss
......[he said:]
Build we a Bower for heavens darling in the grizzly deep,
Build we the Mundane Shell around the Rock of Albion.