Few men are able to shape the world in death as they did in life. To do so is to so subsume your existence to a lofty ideal, with such complete thoroughness, that your life comes to symbolize the values for which you toiled. In the latter half of the 20th century perhaps only two men can be said to have so completely revitalized their communities that they achieved immortality by becoming the symbol of their nations. They are Martin Luther King, Jr., who offered dignity and self-worth to a persecuted people, and the Lubavitcher Rebbe, Rabbi Menachem Schneerson, who...