The quote comes from “Proverbs of Hell,” a chapter in William Blake’s gnostic text The Marriage of Heaven and Hell.
The book has been interpreted as an anticipation of Freudian and Jungian models of the mind, illustrating a struggle between a repressive superego and an amoral id. It has also been interpreted as an anticipation of Nietzsche’s theories* about the difference between slave morality and master morality.
*cf: in particular Nietzsche’s camel – lion – child model of human thought and behavior as outlined in Also sprach Zarathustra: Ein Buch für Alle und Keinen / Thus Spoke Zarathustra: A Book for All and None (1883-1885).
Portions of this post appeared originally on December 5, 2009.