Book excerpt: The metaphor of contagion pervades critical discourse across the humanities, the medical sciences, and the social sciences. It appears in such terms as 'social contagion' in psychology, 'financial contagion' in economics, 'viral marketing' in business, and even 'cultural contagion' in anthropology. In the twenty-first century, contagion, or 'thought contagion' has become a byword for creativity and a fundamental process by which knowledge and ideas are communicated and taken up, and resonates with André Siegfried's observation that 'there is a striking parallel between the spreading of germs and the spreading of ideas'. In Contagious Metaphor, Peta Mitchell offers an innovative, interdisciplinary study of the metaphor of contagion and its relationship to the workings of language. Examining both metaphors of contagion and metaphor as contagion, Contagious Metaphor suggests a framework through which the emergence and often epidemic-like reproduction of metaphor can be better understood.