Trusting George Cheyne: scientific expertise, common sense, and moral authority in early eighteenth-century dietetic medicine.

Whenever physicians give directions to patients there is always a question of their authority to do so: what is it that they know, and who is it that they are, that gives them this authority? The problem is fully general, but it takes especially interesting forms in early modern dietetics, where patients were reckoned to possess much pertinent and reliable knowledge, and where medical dietetics occupied terrain already densely occupied by moral prudence. This article addresses these issues in relation to the writings and practice of George Cheyne (1671-1743), iatromechanist, dietary writer, and fashionable physician. Special attention is given to the relation between Cheyne's scientific expertise and the texture of the advice he gave to two patients, the printer and novelist Samuel Richardson and Selina, countess of Huntingdon.