The role of the healer is expanding. Attempts by physicians to enhance human capacity are but one among many new medical projects. The twentieth century ushered in significant changes in therapeutic modalities, and the past two decades have seen the role of the physician reshaped by economic, political, and dramatic new social mores. People ask new and different things of their clinicians. Under managed care, the primary care clinician is expected to have much more skill than was traditionally expected of a general internist, and new incentives force physicians to much more explicitly ration the care they provide to patients and to patient populations. But perhaps no change in the contemporary world of health portends more long-term effects than the introduction of enhancement technologies.