It is when he walks by night that he stumbles, for he has no light.”
Electricity has softened the power of darkness in our time because even on cloudy nights the sky has a glow from distant cities. In the time of Jesus this was not the case. A light source had to be taken with you if you were to move about during the night or you would fall over every obstacle in your path. If you were not carrying a torch or lantern and you were not near a fire, then darkness was total and complete.
Spiritual darkness is total and complete without Jesus, then, as it is now. He is the Truth (John 14:6) and the Light (John 8:12) and thus He is the only source of both. Without Him we will stumble and fall as we try to find our way through the pitfalls and obstacles we face in our lives. We need Him and the spiritual illumination only He can give.
John 14:6 Jesus answered, “I am the way and the truth and the life. No-one comes to the Father except through me.
John 8:12 When Jesus spoke again to the people, he said, “I am the light of the world. Whoever follows me will never walk in darkness, but will have the light of life.”