The sufferer's experience of illness, although a relatively recent subject of historical research, is not difficult to investigate. In all ages, people have been fascinated by illness. Thus, diaries and autobiographies are replete with descriptions of the disorders suffered by both writers and their family members, friends and acquaintances. Seventeenth century England was rich in such documents. However, historians who have used these source materials have generally been interested in such subjects as politics, religion, economics and family relationships, leaving the great wealth of medical information they contain virtually untapped.

The extent to which diaries reflect general experience is frequently and deservedly questioned. The seventeenth century diarists whose writings have survived were members of the middle and upper classes. Furthermore, diarists and autobiographers are unusual in any age, feeling a need most people never feel to commit thoughts and experience to paper. Their attitudes and behaviour can be taken as representative neither of general experience nor of the experience of others at their social level.

Nonetheless, such records of unique, personal experience are invaluable to the historian, providing as they literally do, a voice from the grave which can make the past live as no other source can. And the fact that the experiences they describe may not be representative is, perhaps, insignificant, since each individual's experience is to a large extent unique, whether or not he or she describes it in a diary.