King David was a great monarch, he was described as "a man after God's own heart" and led his people well. But in this Psalm that King David wrote, he doesn't point to his own greatness or the fame of his kingdom. Instead David points to a better king and a better kingdom. He points to the King of Kings and Lord of Lords Jesus Christ, who's kingdom is without end. In response to such a King and kingdom, David gives praise to the King who's "greatness no one can fathom".