The Seven Nations fled before him: they became what
          they beheld.

Blake makes quite explicit that when sense ratios change, men 
change. Sense ratios change when any one sense or bodily or 
mental function is externalized in technological form:

   The Spectre is the Reasoning Power in Man, & when separated 
   From Imagination and closing itself as in steel in a Ratio
   Of the Things of Memory, It thence frames Laws & Moralities
   To destroy Imagination, the Divine Body, by Martyrdoms & 
        Wars. (1)

     Imagination is that ratio among the perceptions and 
faculties which exists when they are not embedded or outered 
in material technologies. When so outered, each sense and