The biological aspects of the broad problems of medicine have caused but tensions and pressures in recent years. On the one hand, there is always the intellectual search for simple, common, unifying concepts which help hold the exasperating parts of the puzzle together. On the other hand, not only in the multitude of new clinical specialties but in many parts of biological research, special techniques, tests, research methods, and machines proliferate the fragmentation within certain specialties, producing new subspecialties.
One of the last major efforts to provide biology with a centripetal unifying force was Hans Selye's ideas of stress. Though they were too all-encompassing to survive without a multitude of exceptions, the concept stimulated much thought and research. The title of Stevens' book is more ambitious than the realization of his theme, perhaps because of its inherent complexity but equally because of the tentative nature of the house of ideas