 The physiology of the emotions and their implications for medicine was another important theme in early modern philosophy. (Here too the imagination has a role to play.) Descartes considered the emotions central to the treatment of both mental and bodily illness. In doing so, he joined a long and popular medical tradition treating the emotions, including Robert Burton’s Anatomy of Melancholy (1621) and William Falconer’s A Dissertation on the Influence of the Passions upon the Disorders of the Body (1788). Burton’s work was conservative, if eclectic, in its approach to understanding the soul and using the machinery of humours and spirits to explain emotion and temperament. But many other writers borrowed piecemeal from the language of humours and spirits, sometimes embedding it in new physiological accounts, sometimes simply using it to describe various affects. Descartes and Malebranche, for instance, spoke of the animal spirits, but also used such new tools as Harvey’s discovery of the circulation of the blood to explain the bodily effects of emotions.