THE soul must of necessity—if we would attain to the divine union of God—pass through the dark night of mortification of the desires, and self-denial in all things. The reason is this; all the love we bestow on creatures is in the eyes of God mere darkness, and while we are involved therein, the soul is incapable of being enlightened and possessed by the pure and simple light of God, unless we first cast that love away. Light hath no fellowship with darkness, for as St. John saith, ‘The light shineth in darkness, and the darkness did not comprehend it.’
John of the Cross, S., Zimmermann, B., & Lewis, D. (2010). The Ascent of Mount Carmel (15–16). Bellingham, WA: Logos Research Systems, Inc.