 According to Shepherd, we have, at every moment, the unacquired, or native, idea of continued existence. The sensation (idea) of it attends all sensations of the sort introduced by action of the organs of sense (EASP: 13); I call these “sensory sensations”. When the idea of continued existence is formed, it represents the cause of the perceived constancy with which recurring patterns of sensory sensations appear and disappear. When you look at a house while walking by, a series of visual sensations appears and when you retrace your steps a similar series appears in reverse order. More generally, sensations of the motions of your limbs and sensory organs constantly appear in conjunction with trains of sensory sensations which vary with the location of your eyes, hands, and so on. Each different sensation has a different cause. But repeated perception of the constant conjunction of sensations of motions of the sensory organs and sensory sensations prompts reason to generate the idea of the continued existence of their causes in accord with the implicit argument: unless things are created purposely in order to be ready to  appear, they must continue to exist ready to appear if suitably related to organs of sense (EASP: 13–14). If it were the case that the causes of sensory sensations arose and perished as the sensations do, then sensible objects, bodily organs, space, time, and everything else required for perception, would arise just when needed for perception and perish immediately afterward. The argument is meant to expose the utter absurdity of this. 