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

“In his time educated people believed that they amused themselves with books of imagination but that they ‘made their souls’ by listening to sermons and by doing or by not doing certain things. When they had to explain why serious people like themselves honoured the great poets greatly they were hard put to it for lack of good reasons.” [via]

Consider also:

  1. “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 things–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.”
  2. “We write of great writers, even of writers whose beauty would once have seemed an unholy beauty, with rapt sentences like those our fathers kept for the beatitudes and mysteries of the Church; and no matter what we believe with our lips, we believe with our hearts that beautiful things, as Browning said in his one prose essay that was not in verse, have ‘lain burningly on the Divine hand,’ and that when time has begun to wither, the Divine hand will fall heavily on bad taste and vulgarity.”
  3. “The technique of Blake was imperfect, incomplete, as is the technique of well-nigh all artists who have striven to bring fires from remote summits; but where his imagination is perfect and complete, his technique has a like perfection, a like completeness.”
  4. “This letter may have been the expression of a moment’s enthusiasm, but was more probably rooted in one of those intuitions of coming technical power which every creator feels, and learns to rely upon; for all his greatest work was done, and the principles of his art were formulated, after this date. Except a word here and there, his writings hitherto had not dealt with the principles of art except remotely and by implication; but now he wrote much upon them, and not in obscure symbolic verse, but in emphatic prose, and explicit if not very poetical rhyme.”
  5. “The reason, and by the reason he meant deductions from the observations of the senses, binds us to mortality because it binds us to the senses, and divides us from each other by showing us our clashing interests; but imagination divides us from mortality by the immortality of beauty, and binds us to each other by opening the secret doors of all hearts.”