A beautiful definition of epidemiology
"Although it is often assumed to be limited to the investigation of epidemics, epidemiology is more properly considered either the study of patterns of disease occurrence in human populations or, even more broadly, the comparison of rates of occurrence of phenomena in various populations so as to increase understanding of the human situation. Epidemiology is commonly considered one of the subdisciplines of medicine, which -- like other professional disciplines -- is often seen as antithetical to the liberal arts. In some ways that characterization of the professions is fair. Certainly, the arcane nature of the professions, with their heavy emphasis on detailed information, the repetitive application of knowledge to solve common problems, and the narrowness of the scope of inquiry suggest that professional studies are inappropriate for an undergraduate liberal arts education. But epidemiology as a professional discipline is anomalous. The heavy emphasis on the method of inquiry, rather than specialized information, is distinctive. Its usefulness as a technique for taking a first pass at a new problem makes it applicable to a wide range of interesting phenomena. And the fact that it is a "low-technology" science makes it accessible to many who are more interested in clear thinking than in complicated laboratory experimentation."
Emphasis is mine. From: Fraser DW. Epidemiology as a liberal art. N Engl J Med. 1987 Feb 5;316(6):309-14.