We are, in a sense, positioned between the interstitial non-space of chapters four and five, and I think for my part, it's time to take an inventory of the concepts that we've introduced and think about them generally.
Firstly, Urizen is the personification of negation. He is associated with Priests, and Scientists, being criticized in fact on the same grounds. Blake is under no obligation to criticize science and scientific materialist philosophy, and in fact could have an apt ally if in fact his war was more focused on social bondage and political reality of his time.
Well, Blake's war is not against the individual priests who have made the choice to reject pleasure, it's against the impulse to impose a system specifically adapted to their own short comings on the lot of us all.
Science in this regard is no better, pretending to a truth which is an abjection of the senses and non-reasoning forms of intelligence.
Blake believes that man has a four-fold personality, but his sense of dimensionality is 2^3 or 3^2, ie: 8,9, or 8*9 = 72 = 2^3 * 3^2. In fact, you have to convert the whole thing over to 72, a mystical number indeed, especially if you want to "rearrange your base".
The reasoning intelligence, Urizen, which is depicted by Blake as asleep is one of four parts to the intelligence or "divine soul" of man. For that idea think of an Adam Kadmon, or a general template, a seed of humanity, which is sort of archetypal.
Freud, Jung, Lacan, all want to create a map of the psyche. Well, so does Blake. He is going to see the Bible, and all sacred codes as projections. Modern psychoanalytic concepts of projection are applicable. Modern mathematical concepts dealing with projection geometry are also applicable. The ability to map data from the physical world, and reshape it, so that you can see it as a Gestalt as a whole... That is the impulse and desire of understanding.
We leave Urizen standing, as Los was before described, with his feet hovering over an Abyss. This stands in contradistinction to the Void which Los stood over, perhaps now being aspected differently. The aspect in Blake is matter of perspective. The image of Christ with his hands pointed up and down, is a gesture, signifying the judgment of God and the Eternal abodes which await each soul. It signifies moral choice and fear of damnation. And here Urizen stands at once in the image of the fearful shepherd, protecting his flock from myriad goats. He is a Divider, not a uniter. He does not wish to bring men together, but to tear them asunder. From this a civil war of the soul is born, the same way men war over ideology. The caution of our conservative sensibilities forever wars against every natural impulse of the body.