The soul must pass through the dark night of the senses because all the passions it feels for created things are pure darkness in God's eyes," wrote the Spanish mystic Saint John of the Cross in the late 16th century. In Ascent of Mount Carmel: John of the Cross, John discusses the soul's need to pass through spiritual darkness before union with the divine can be possible. In a beautiful text that has been "edited and mildly modernized" by Henry Carrigan Jr., John offers an early treatise on his spiritual poetry, outlining themes that he fleshed out more fully in his more famous later work, Dark Night of the Soul.