It is a great pleasure and a privilege to join with Dr. Castle's friends, colleagues, and former students in celebrating his 60th birthday by contributing to aFestschriftin his honor. Although the note which I will introduce stems from my work in psychiatry and psychoanalysis, I believe that it is nevertheless fitting for the occasion. I propose to consider the similarities and differences between medicine and psychiatry. This subject is usually debated in informal gatherings in a personal and impressionistic fashion. Instead of this approach, my purpose here is to present a scientific inquiry into this subject, meaning thereby an examination of medicine and psychiatry as bodies of knowledge, methods of treatment, and professional roles in society. The Common-Sense Approach to Medicine and Psychiatry I shall begin with what may be called the common-sense approach to medicine and psychiatry. According to this view, medicine comprises a very large area