William Blake and his Illustrations to The Divine Comedy in Ideas of Good and Evil by William Butler Yeats.

“The errors in the handiwork of exalted spirits are as the more phantastical errors in their lives; as Coleridge’s opium cloud; as Villiers De L’Isle Adam’s candidature for the throne of Greece; as Blake’s anger against causes and purposes he but half understood; as the flickering madness an Eastern scripture would allow in august dreamers; for he who half lives in eternity endures a rending of the structures of the mind, a crucifixion of the intellectual body.” [via]

Consider also:

  1. “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.”
  2. “His praise of a severe art had been beyond price had his age rested a moment to listen”
  3. “There are many mediums in the means–none, oh, not a jot, not a shadow of a jot, in the end of great art. In a picture whose merit is to be excessively brilliant, it can’t be too brilliant, but individual tints may be too brilliant…. We must not begin with medium, but think always on excess and only use medium to make excess more abundantly excessive.”
  4. “Blake represented the shapes of beauty haunting our moments of inspiration: shapes held by most for the frailest of ephemera, but by him for a people older than the world, citizens of eternity, appearing and reappearing in the minds of artists and of poets, creating all we touch and see by casting distorted images of themselves upon ‘the vegetable glass of nature’; and because beings, none the less symbols, blossoms, as it were, growing from invisible immortal roots, hands, as it were, pointing the way into some divine labyrinth.”
  5. “the merely mortal part of the mind, ‘the spectre,’ creates ‘pyramids of pride,’ and ‘pillars in the deepest hell to reach the heavenly arches,’ and seeks to discover wisdom in ‘the spaces between the stars,’ not ‘in the stars,’ where it is”