Power of belief

The Nameless One: If there is anything I have learned in my travels across the Planes, it is that many things may change the nature of a man. Whether regret, or love, or revenge or fear — whatever you believe can change the nature of a man, can. I've seen belief move cities, make men stave off death, and turn an evil hag's heart half-circle. This entire Fortress has been constructed from belief. Belief damned a woman, whose heart clung to the hope that another loved her when he did not. Once, it made a man seek immortality and achieve it. And it has made a posturing spirit think it is something more than a part of me.
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Changing human nature