"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."
-John Newton, The Letters of John Newton, pg. 320
"Christ's enemies are but breaking their own heads in pieces, upon the Rock laid in Zion; and the stone is not removed out of its place. Faith hath cause to take courage from our very afflictions; the devil is but a whetstone to sharpen the faith and patience of the saints. I know that he but heweth and polisheth stones, all this time, for the new Jerusalem."
-Samuel Rutherford, The Letters of Samuel Rutherford, pg. 231