In his seminal book Good to Great, Jim Collins describes the Stockdale Paradox as a critical leadership principle that separates great leaders from good ones. The principle is named after the highest-ranking military officer prisoner of war during the Vietnam War, Admiral Jim Stockdale, who never lost faith despite grim realities he and others faced. Collins describes the Stockdale Paradox as the concept that you must retain unwavering faith that you will prevail in the end, regardless of the difficulties, and at the same time confront the most brutal facts of your current reality, whatever they may be.