[Interpretative margins and narrative authority in the autobiographical account of illness].

Patients' letters are among historical sources that have been recently put forward in the history of medicine in order to shed light on the perspective of the sick and explore the dynamics of therapeutic relationships. They enable historians to focus on the active participation, initiatives and strategies of lay people in the handling of their health and illness. Based on the analysis of letters written by patients to the Swiss physician Samuel-Auguste Tissot in the second part of the 18th Century, this paper deals with the relative autonomy that sick people are able to claim in the process of interpreting and explaining of their medical trajectories. It is argued that they possess a "narrative authority", which can be defined as the possibility to defend one's own point of view in the organisation of one's narrative, thanks to the interpretative latitude due to polyphony and plurality of meanings inherent in the intersubjective construction of the illness experience.