A Memorable Fancy

As I was walking among the fires of hell, delighted with the enjoyments of Genius; which to Angels look like torment and insanity. I collected some of their Proverbs: thinking that as the sayings used in a nation, mark its character, so the Proverbs of Hell, shew the nature of Infernal wisdom better than any description of buildings or garments.
When I came home; on the abyss of the five senses, where a flat sided steep frowns over the present world. I saw a mighty Devil folded in black clouds, hovering on the sides of the rock, with corroding fires he wrote the following sentence now percieved by the minds of men, & read by them on earth.

How do you know but ev'ry Bird that cuts the airy way,
Is an immense world of delight, clos'd by your senses five?

William Blake