17. Just as it is impossible for the eye to perceive sensible objects without the light of the sun, so the human intellect cannot engage in spiritual contemplation without the light of the Spirit. For physical light naturally illuminates the senses so that they may perceive physical bodies; while spiritual light illumines the intellect so that it can engage in contemplation and thus grasp what lies beyond the senses.
I appreciate St. Maximos’ comparison here between our ability to perceive with our physical and spiritual eyes. In both cases, we require illumination. Absent that illumination, we are in darkness.