If we neglect or relax for a moment our spiritual defenses we can be quickly swept over by the seemingly overwhelming array of tribulations presented by mortal mind via so-called material existence. In desperation or resignation we may retreat into the comforting confines of our home sanctuary and assume that at least the "out there" isn't "in here" and can't get in.
Yet not only would this be disobeying the commands of Christ Jesus and Mrs. Eddy to resist the devil, but an important lesson would be delayed: that the only "out there" is always "in here", within our own thinking. We only experience what we admit into, and what therefore exists in, our consciousness, and once there, false belief has no difficulty coming home with us as an unwelcome houseguest. The work of silencing or resisting error's claims is a full-time task, and the mental ground may have to be carefully gone over hundreds of times to assure the adversary's full and final eradication . We must destroy, not merely ignore or parley with, what Mrs. Eddy calls "personal sight or sense".
To see, hear, or experience anything but God's omnipresence, omnipotence, omniscience, and omni-action is to entertain and rehearse something that never did, or even could, exist. This may be easy to grasp intellectually, but it must be sedulously demonstrated spiritually, metaphysically, if we are ever to free ourselves forever from the nothingness "out there". That is why ceaseless study, prayer, and practice are essential, and if it is sickness that herds us eftsoons into the schoolroom which directs us to Christ, we should be grateful for the experience.