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

“He announced the religion of art, of which no man dreamed in the world about him; and he understood it more perfectly than the thousands of subtle spirits who have received its baptism in the world about us, because, in the beginning of important thingsā€”in the beginning of love, in the beginning of the day, in the beginning of any work, there is a moment when are understand more perfectly than we understand again until all is finished.” [via]