Cheerfulness in the history of psychiatry.

In 1762, Louis-Antoine Marquis de Caraccioli (1719-1803), a prolific writer of the eighteenth century, dedicated a book to a psychological theme that medicine has forgotten: '

Déclaration de conflit d'intérêts

Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.