This book has been about policing the boundaries of material quality using the moral authority of nature. 2 It has addressed the means by which cow’s milk has been manipulated in its composition over a period of 200 years, 1800 to date. Although naturalized to the point of being taken for granted, this organic fluid in reality has been a coeval participant and powerfully influential in the scientific, commercial and political interests that have emerged to shape the modern food system. Building an understanding of such commodities helps us grasp our mutually-constituting relationship with food, which is among our immanent and most intimate contacts with nature.