In which genre is "The Marriage of Heaven and Hell" categorized?

"The Marriage of Heaven and Hell," written by William Blake, is categorized as poetry. This work is part of Blake's larger body of poetic and prophetic literature, which blends elements of both personal vision and philosophical exploration. The piece employs a distinct style that combines lyrical verse with a complex structure, including the use of invocations, philosophical dialogues, and a free verse rhythm that is characteristic of Blake's innovative approach to poetry.

In addition, the work's thematic exploration, including the tension between opposing forces such as good and evil, reflects the qualities of poetry, particularly in the Romantic tradition, where emotional expression and imaginative language are central. Other genre options like drama, essay, and novel do not apply here as those forms adhere to different conventions and structures than what Blake employed in this particular piece of writing.