I notice the Psalm changes from the third person in the first 3 verses to the first person in verse 4 and 5, then back to the reflection of the third person in verse 6. It's as if David, having first started thinking of God, can't help but start talking to Him. Then, having spoken to God briefly, he goes back to thinking about his life and the difference knowing God makes for him.
I have always considered the Psalms to be David's prayer journal. He writes out his joys and woes, his concerns and his exaltation. Psalm 23 seems to fit that profile. Perhaps it was his short meditation written at the end of a hard day in one of the many battles he fought. He sounds as if he was longing for the days when he was a shepherd who just had to look after sheep. Now he looks after a kingdom and an army of men who depend on him.
One of the most memorable reflections on this Psalm that I have ever read was included in a book written by a man who was a long-held prisoner of war in Vietnam. He and the other captives were held in primitive conditions, with no reading material, and only secretive communications among themselves. One way they maintained their sanity was to recall any bit of Scripture that they could. These Scriptures were words of encouragement to keep one other from despairing and they devised a method of communicating these Scriptures to each other. Psalm 23, of course, was one that they remembered and which became a theme for the book.
What about now? What is important for me in reading it today? I've never been to war and never been a shepherd. I am not in mourning for a loved one. So today I proclaim: The Lord is my shepherd. I want for nothing. We lie down together in green pastures, beside restful waters, and he restores me.