There's an urban legend that after people die, their weight drops by twenty-one grams. They say that's the weight of the soul.
There's also the idiom "to lose one's soul." Its true meaning is literal: to have one's soul taken away. But this isn't about being frightened. After certain experiences and encounters, powerful emotions can cause you to leave your soul behind in someone else, or in some thing.
People like this cannot pass on to the next life. And so a certain kind of person came into being: soul collectors.
