Hopelessness - The driving force behind TLOTR
As long as we have hope, there is something we may turn to. A chance, a maybe. We still have something to lose if we mess up. But if we lose that something, and have no hope left for the world, we become more dangerous than any other.
What then, has this to do with The Lord of the Rings? It's very simple. If I may take back your memory to the Return of the King. . . .
. . . Even as Sam lost all hope, or seemed to, a new strength grew in him . . .
It's paraphrased, but the truth is the same. Sam had lost all hope, and Frodo before that. Both hobbits believed very much that they would die, and in such, Frodo, at least, had nothing to lose. So he might as well go on. Sam was a little better off, but he, too, was lost in a world of hopelessness.
Far away, we come to Eowyn as she faces the Witch King. The woman truly believed she would die -- and had she not just lost all hope in her father? She had no hope left, nothing to live for. And that made her stronger than she had ever been before.
These two instances are simple, but had not the two hobbits and woman lost all hope and everything to live for, the Ring and Witch King may not have been destroyed. In their hopelessness, they became strong.
True, it may be impossible to lose all hope, and hope can be the driving force in people, but most of the time there is no one more dangerous or more strong than one who was nothing to live for, and no hope of living anyway. That is the lesson we learn from The Lord of the Rings.