'Do No Harm' is a book by Henry Marsh, and he reflects on his career mistakes and things he wished he would have done differently. It is a retrospective look on his life and career. It deals with death or disability to some of his patients, despite his best intentions at making them better and taking away their ailments and pain. These unwanted outcomes came from a variety of reasons. Marsh was not affected any differently by a patient's death, regardless of whether it came from a direct fault of Marsh's or by other means. Regardless of his decision of treatment for a patient, either one type of treatment versus another or no treatment at all, Marsh took the responsibility on himself personally rather than putting it on fellow staff or the hospital. Marsh developed a trust with his patients, which allowed him to better treat them or formulate a plan by which to treat them.