The placebo has been part of the physician’s toolkit since the earliest days of medicine. Plato noted a physician’s power to heal through “words and phrases.” In Mesmer’s time, placebos were commonplace. Thomas Jefferson once confided that “one of the most successful physicians I have ever known has assured me that he used more of bread pills, drops of colored water, and powders of hickory ashes, than of all other medicines put together.”
