The ground of this efficacy of sin by deceit is taken from the faculty of the soul affected with it. Deceit properly affects the mind; it is the mind that is deceived. When sin attempts any other way of entrance into the soul, as for example by the affections, the mind—retaining its right and sovereignty—is able to give check and control to it. But where the mind is tainted, the prevalence of sin must be great, for the mind or understanding is the leading faculty of the soul.