Daniel Callahan, an American philosopher and biomedical ethicist, discusses how the field of medicine has changed over time from an ethical perspective. Callahan co-founded the Hastings Center, an influential bioethics research institute in New York. This is the second part of a two-part series about health care in the 21st century. Callahan proposes that the history of medicine can be broken down into three distinct phases. The first phase, which he labels the “pre-scientific stage,” includes most of human history before the scientific understanding of disease. In this phase, Callahan argues that the role of medicine was primarily one of care and compassion rather that curing illnesses. The second phase, which he refers to as “scientific medicine,” began in the early twentieth century and was “marked by the conscious application of scientific medicine to human illness.” During this time, medicine advanced rapidly and medical ethics came to fruition as a field. Concerns like patient rights, allocation of resources, equality, and justice became topics of public and academic discussion. Callahan argues that medicine is at the precipice of a new stage, the third stage, of theory and practice. He proposes that this stage will include compromises and a fundamental re-thinking of what medicine is and what role it serves. The lecture is followed with questions from the audience. Recorded November 7, 1991 at The 92nd Street Y, New York.