Bills of Mortality and illness identification

Left, "The Good Man at the Hour of Death" -- Death is elderly with wings and hourglass.
Right, "The Bad Man at the Hour of Death" -- Death is skeleton with spear.
(Source:  Wellcome Museum special exhibition, "Death, A Self-Portrait," accessed 18 November 2012.)

Registration of deaths and disease classifications go hand-in-hand.  The recording of death causes began in Italy in the 15th century, and officially began in London in 1532.  Searchers determined the cause but would consult a physician in more difficult cases.  Although we think of them as poorly trained, they were identified as "wise women."  Their reports were given to the parish clerk weekly, who then totalled up the causes and published the results on Wednesdays (Moriyama, Iwao, Ruth Loy, Alastair Robb-Smith, MD.  History of the Statistical Classification of Diseases and Causes of Death (ed/updated Harry Rosenberg and Donna Hoyert).  (Washington, DC:  National Center for Health Statistics/CDC, 2011), 1-2).
John Graunt (1620-74) used the Bills to make generalizations about about mortality, including that a third of all children in London died before the age of five (Moriyama, 2).  The Bills were not used in the 18th century for doing anything more than tracking disease -- it would not be until 1854 that they would be used by John Snow to identify the source of a cholera outbreak and therefore change the environment (eliminate the water pump where the cholera-infected water was coming from).  For more information about his fascinating story, check http://en.wikipedia.org/wiki/John_Snow_(physician).
We now know that many of the categories in a Bill of Mortality could describe the same illness, or a symptom could be attributed to many illnesses.  So although the searchers did the best they could, it became obvious in the century after Methodism began that a classification of naming illnesses was crucial for good illness prevention and disease control.  In 1839, the first Annual Report of the Registrar-General of England and Wales stated, "The advantages of a uniform nomenclature, however imperfect, are so obvious, that is tis surprising no attention has been paid to its enforcement in the Bills of Mortality.  Each disease has, in many instances, been denoted by three or four terms, and each term has been applied to as many different diseases; vague, inconvenient names have been employed, or complicatons have been registered instead of primary diseases.  The nomenclature is of as much importance in this department of enquiry as weights and measures in the physical sciences, and should be settled without delay." (Moriyama, 5).
My point in telling you all this is to remind you that today we are told by our medical care providers exactly what we have, or a best educated guess as to what we are ill with.  There was no such system in the time of the early Methodists.  So if nobody knew what was wrong with you, there was no organized system to figure out what people actually were sick with, how would anyone know what was an effective treatment for your illness?  You can understand how Methodists would be grateful for a book of treatments from John Wesley, whom they trusted and respected.