The possibility of madness is therefore implicit in the very phenomenon of passion.
This quotation reveals Foucault's radical interpretation of seventeenth-century theories of the passions. Traditionally, the passions were seen by writers like Descartes and Hobbes as feelings or movements within the mind that produced a bodily action. Lust, envy, fear and desire were all passions. The passions were usually opposed to reason, and seen as having dangerous effects. Because they began in the mind and ended with a physical action, they represented a way of uniting mind and body. They were also associated with a temporary kind of madness by many ancient writers. Foucault takes this idea one step further by arguing that any phenomenon which links mind and body allows a disease like madness to affect mind and body. In doing so, he relates the passions to another important seventeenth-century concern: the relationship between mind and body. Although this is an interesting idea that links philosophical approaches to the mind with madness and medicine, not all authors who discussed the passions made the same connections as Foucault.