William Blake and the Imagination in Ideas of Good and Evil by William Butler Yeats.

“But when one reads Blake, it is as though the spray of an inexhaustible fountain of beauty was blown into our faces, and not merely when one reads the Songs of Innocence, or the lyrics he wished to call ‘The Ideas of Good and Evil,’ but when one reads those ‘Prophetic Works’ in which he spoke confusedly and obscurely because he spoke of things for whose speaking he could find no models in the world about him.” [via]