IT SEEMS only fair to begin with a confession: the preparation of this article has been more difficult than of any I can recall with a memory that is assuredly less precise than it once was, but still seems sufficiently intact to be reasonably dependable. While struggling at my desk to find words that might be useful, I found myself leafing through earlier correspondence with Dr Thomas Zimmerman and discovered in a letter that I received from him five years ago the probable source of this present difficulty. He was commenting on a paper I had delivered to the Alliance for Continuing Medical Education, one that ended with an implied promise that it represented "a final contribution to the debate in which I have taken part for nearly twenty years." Dr Zimmerman replied that he was appointing himself "a committee of one to be sure that this is not your last public