I was driving near the border of Nevada about a week ago, when I saw a sign, Martin Luther King Jr. Highway. My mind instantly raced back 40 years. I remember being moved as I watched this mesmerizing orator on television as he spoke outside the Lincoln Memorial. Even Walter Cronkite said about him, ''I only met Martin Luther King on a few occasions but I was always struck by the obvious force, the power of his character.'' King's life and death is the stuff of legend now. But it's what he couldn't do that causes me to wonder today....