The Howard Starks in Robin Cook novels are throwbacks to the deadly mad scientist — often a physician — who recurs in such Nathaniel Hawthorne stories as "The Birthmark" and "Dr. Heidegger's Experiment." In "Rappacini's Daughter," Hawthorne wrote: "His patients are interesting to him only as subjects for some new experiment. He would sacrifice human life, his own among the rest, or whatever else was dearest to him, for the sake of adding so much as a grain of mustard seed to the great heap of his accumulated knowledge."