 But he should have realized that Asenath's (possibly Ephraim's) soul is partially detached from her body, and that the soul will live on until the body is cremated.Asenath had succeeded in taking control of his body while he was in the sanitarium, which means that "the thing on the doorstep" is actually Derby inhabiting Asenath's putrefying corpse.The note implores Upton to go to the sanitarium to kill Derby, who has now been permanently possessed by Ephraim's soul the way he imagines the original Asenath once was.