I am deeply grateful to my fellow members of the Douglas Fir Group for the wide ranging intellectual discussions that led up to the publication of the 2016 co-authored article, which inspired this book. I am also indebted to the following graduate students who read various chapters and offered insightful comments and suggestions: Michael Amory, Yingliang He, Olesya Kisselev, Tianfang (Sally) Wang, and Rebecca Zoshak. Special thanks to my colleague, Karen Johnson, for her collaboration and contributions, and to Yingliang and Sally who provided enormous help in compiling reference lists and from whose copyediting skills I benefited greatly. Finally, I thank the publishing team at Routledge for their patience and support in seeing this project through to completion.