Blake makes quite explicit that when sense ratios change, men change. Sense ratios change when any one sneer 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 Martrydoms & Wars. Blake’s view was that [quoting Northrop Frye] “history as linear time is the great apocrypha or mystery which has to be ‘rejected’ since “the whole of human life is seen and understood as a single mental form.” (p. 340) The linear view of history began with Petrarch and Leonardo da Vinci and ended with Gibbon and Hume. So obsessive a metaphor as that of linear perspective is important enough to deserve some explanation, especially since we are now deep in the process of extricating ourselves from it.