There are four questions which in some form or other every patient asks his doctor: (a) What is the matter with me? This is diagnosis. (b) Can you put me right? This is treatment and prognosis. (c) How did I get it? This is causation. (d) How can I avoid it in future? This is prevention.
Preventive Medicine for the Medical Student, The Lancet, Volume 221, November 21, 1931 (p. 113)