If the doors of perception were cleansed everything would appear to man as it is, infinite.

Largely unrecognised during his lifetime Blake is now considered a seminal figure in the history of the poetry and visual arts of the Romantic Age. A more recent (and very short) study William Blake: Visionary Anarchist by Peter Marshall (1988) classified Blake and his contemporary William Godwin as forerunners of modern anarchism. In Visions Blake writes:

In the 19th century poet and free love advocate Algernon Charles Swinburne wrote a book on Blake drawing attention to the above motifs in which Blake praises "sacred natural love" that is not bound by another's possessive jealousy the latter characterised by Blake as a "creeping skeleton".

His paintings and poetry have been characterised as part of the Romantic movement and "Pre-Romantic" for its large appearance in the 18th century. Reverent of the Bible but hostile to the Church of England – indeed to all forms of organised religion – Blake was influenced by the ideals and ambitions of the French and American revolutions as well as by such thinkers as Jakob Böhme and Emanuel Swedenborg. Despite these known influences the singularity of Blake's work makes him difficult to classify.