Man derives the knowledge that he is living in a fallen world from the contrast between his desire and his power, between what he would like to do and what he can do. Lockian common sense makes the least of the former and the most of the latter; Blakean genius always suffers from claustrophobia. Between these are ordinary men whose feelings of dissatisfaction are choked down and suppressed whenever they recur, until a reservoir of anguish and fury is stored up which periodically floods the world in revolution. Revolution is the sign of apocalyptic yearnings, of an impulse to burst loose from this world altogether and get into a better one, a convulsive lunge forward of the imagination.