THE EPIDEMIOLOGICAL POINT OF VIEW *

The material of the epidemiologist is not peculiar to liirn ; fifee the clinician and the pathologist lie devotes himself to the study of disease in its varied form?; all see the same objects, but they see them from different points of View. If we wished to stndy the acchitecture and topography of this city of Cambridge we could adopt one of three courses. We might go through the streets and colleges with agnide; weimght select some representative building for special study ; or we ?light obtain a bird's-eye view of all from -an aeroplane. Each method has its Advantages and disadvantages. The first must be pre ferred if it is roest important to tts'to learn how to go quickly from one part of the city to another, and to recog ??ze wJhat we see in, passing ; the second gives a mastery ?id appreciation of intimate detail ; the third brings out the inter ?elatioas of different parts. In medicine, the first method is that of thepraet?sn^goliB?cian; the second that of the scientific pathologist ; the third that of the epi demiologist. The science of general medicine should integrate .results obtained by the several methods. The epidemiologist is therefore an observer from the mountain top, concerned with disease as a mass phenomenon; his busisess is not with individuals but with Aggregates. He seeks to define the relations of these aggregate*, the general arrangement of tice streets in the c?ies of the plain, but is sot concerned with details. This points view was oace adopted by all physicians, and some have accordingly argued that the duty of an epidemiologist is to take Hippocrates as his guide, and to seek intellectual salvation amid the classical writers. But there are objections to this theory. When there are no paths down from the mountain to the cd ties of the plain, jtbe inhabitant of the mommtaio must content himself with distant views. If Hippocrates liad had a modern equip ment he might still have preferred the method he actually adopted ; hut he might not have done so ; he had no choice. There is also a practical difficulty in attempting to adopt the classical standpoint?the danger of finding hi ancient writings what is not there. Let me give an example. In the third book of the Epidemics the following passage occurs :