The still, deep waters of sin

Sin doth not only still abide in us, but is still acting, still labouring to bring forth the deeds of the flesh. When sin lets us alone, we may let sin alone: but as sin is never less quiet than when it seems to be most quiet, and its waters are for the most part deep when they are still, so ought our contrivances against it to be vigorous at all times, in all conditions, even where there is least suspicion.

-John Owen, from The Mortification of Sin