The dark night of the soul takes its name from a poem and the accompanying prose commentary written by the sixteenth century Spanish Carmelite friar John of the Cross, describing the soul's passage away from reliance on sensory devotion and consoling spiritual experience toward a purer, more difficult union with God. John distinguishes two nights: the night of the senses, in which the beginner's reliance on pleasurable feelings in prayer is stripped away, and the far more severe night of the spirit, in which even the soul's deeper faculties are purified through a sense of God's absence, dryness and apparent abandonment.
The darkness is not, in John's account, a sign of spiritual failure or divine punishment but the opposite, a necessary and God given purgation that clears away everything that is not God so that the soul can be united to God more completely than consoling experience alone would allow. The poem's central image, a soul slipping out in secret at night to meet its beloved, frames what could read as pure desolation as, underneath, a love story, the night as the necessary darkness in which the most important meeting can happen. John composed both the poem and its extended prose commentary while himself imprisoned by fellow Carmelites opposed to his reform efforts, a biographical detail that has shaped how later readers understand the darkness he describes.