I don't know how to introduce, to describe William Blake. He was simply one of the most influential and unique figures in the history of art. What else can compare to his works or is like them? Strange and stranger. Obviously a significant portion of his genius came from his insanity, all in the forms of wild and vivid images.
Behemoth and Leviathan
c. 1805 - 1810
Lucia Takes Dante to the Entrance of Purgatory
Blake is also very well known for his poetry:
Ah, sunflower, weary of time,
Who countest the steps of the sun;
Seeking after that sweet golden clime
Where the traveller's journey is done;
Where the Youth pined away with desire,
And the pale virgin shrouded in snow,
Arise from their graves, and aspire
Where my Sunflower wishes to go!
Antaeus sets down Dante and Virgil in the 9th circle