"The Dark Night of the Soul" by St. John of the Cross
"The Dark Night of the Soul" is a treatise commenting on the poem of the same name (and containing the poem itself), written by 16th-century Spanish poet and Roman Catholic mystic St. John of the Cross. The poem narrates the journey of the soul from its bodily form to its union with God. (Wikipedia: https://en.wikipedia.org/wiki/Dark_Night_of_the_Soul)
