This is just a theory...

The power that controls this reality is able to access the body, the mind, and even the spirit. The essence of the spirit is the will of the spirit. The will of the spirit is the fourth substantial element. To enter and subdue the heart of the mind is to control the will of the spirit. The will of the spirit is, I believe, that which defines the worth of the spirit in the eyes of the creator. The will of the spirit is not unbreakable. Every living existence has the ability to break and conform to the will of another existence. Even so, the spirit is judged by how long it persists with its personal logic when choice is present. For a creature such as a saint, the will of the spirit is only truly broken through an experience similar to a crucifixion.