Yea, though I walk through the valley of the shadow of death, I will fear no evil: for Thou art with me; Thy rod and Thy staff they comfort me. Psalm 23:4
So far, David has been using the third person to describe the journey. “He leadeth … He maketh me to lie down … He restoreth.” Suddenly death looms on the horizon and instantly David drops the third person for Thou! He is no longer talking about the Shepherd. He is talking to the Shepherd.
Note that this is only the valley of the shadow of death. The shadow of a dog cannot bite, the shadow of a sword cannot kill, and the shadow of death cannot harm the child of God. Where we have a shadow we have two other things—a substance and a light. David has already talked about the substance of death in Psalm 22: “My God, My God, why hast Thou forsaken Me?” That is what Jesus cried at Calvary. The very substance of death is to be forsaken of God. That is the essence of a lost eternity—to die, God-abandoned. That is what awaits those who die without the Shepherd.
Where there is a shadow, there must also be a light. It is the light shining on the substance that casts the shadow. This is what makes the difference between the death of a believer and the death of an unbeliever. The unbeliever goes out into the dark. There is reserved for him the “blackness of darkness forever” (Jude 13). It would be hard to imagine a greater horror than to be lost and alone in eternal darkness.
The believer, however, goes out into the light. “I will fear no evil: for Thou art with me.” There we have the assurance of the presence of the Shepherd when we come face to face with the tomb.
—From Exploring the Psalms by John Phillips