Jonathan Gil Harris examines the origins of modern discourses of social pathology in Elizabethan and Jacobean medical and political writing. Plays, pamphlets and political treatises of this period display an increasingly xenophobic tendency to attribute England's ills to 'foreign bodies' such as Jews, Catholics and witches, as well as treat their allegedly 'poisonous' features for the health of the body politic. Harris argues that this tendency resonates with two of the distinctive paradigms of Paracelsus' pharmacy which also includes the notion that poison has a medicinal power. The emergence of these paradigms in early modern English political thought signals a decisive shift from Galenic humoral tradition towards twentieth-century politico-medical discourses of 'infection' and 'containment', which, like their early modern predecessors, make mysterious the domestic origins of social conflict and the operations of political authority.