Hippocrates’ Oath and Asclepius’ Snake: The Birth of the Medical Profession articulates the Oath as establishing the medical profession—a practice incorporating an internal, uniquely medical ethic that particularly prohibits doctors from killing. In its most basic and least controvertible form, this ethic mandates that physicians try to help while not trying to harm the sick. Relying on Greek myth, drama, and medical experience (e.g., homeopathy), the book shows how this medical code arises from reflection on the most vexing medical-ethical problem: iatrogenic harm, injury caused by a physician. The book argues that deliberate iatrogenic harm—especially the harm of a doctor choosing to kill (physician-assisted suicide, euthanasia, abortion, and involvement in capital punishment)—amounts to an abandonment of medicine as an exclusively therapeutic profession. Since electively killing a patient always injures (even when done at the patient’s request), the Oath excludes killing (along with other salient harms such as sexual exploitation and the violation of patient confidentiality) from medicine as a profession. The work argues that medicine as a profession necessarily involves stating before others what one stands for: the goods one seeks and the bads one seeks to avoid on behalf of the sick. The book considers and rejects the view that medicine is purely a technique lacking its own unique internal ethic. It concludes by noting that medical promising (as found in the White Coat Ceremony by which US medical students matriculate) implicates medical autonomy, which merits respect, including the honoring of professional conscientious objection.