Cao Pi nods firmly. "Then we will list that as something to investigate, or work on, should someone with the means to experiment be among us now. It is nothing I, nor the inspector nor commander, are experienced with, it will have to be someone else's realm.

"That said," he adds, somewhat cautiously, "I don't wish to rule out anything that can and will work. If there is a way to make an invisible barrier, I would like to see it tried. If there is any other idea, no matter how far-fetched, it should be considered. If the spirits among us actually agree that their more vicious overlords are not to be trusted, then perhaps we can enlist their help rather than push them out."