We have no clear ideas of the agency of [demonic] spirits,...

We have no clear ideas of the agency of [demonic] spirits, nor is it necessary. The Scripture says little to satisfy our curiosity; but tells us plainly that he is always watching us, and desiring to sift us as wheat. I believe we give him no more than his due, when we charge him with having a hand in all our sins. I believe he cuts us all out abundance of work.