Dr. David Hilfiker is a physician who left a rural family practice in Minnesota to treat the urban poor. In his new book, "Not All of Us Are Saints," he describes his frustration both with the system that allows people to live in poverty, and with the patients who frequently flout his medical advice. Hilfiker's first book, "Healing the Wounds" won the "American Medical Writers Associatin" prize, and was named among the "Best Books of the Year" from the NYT Book Review.