This book owes an immense and obvious debt to the Berkeley linguistic community. The largest debt of all is to my thesis committee: Charles Fillmore, George Lakoff, and Paul Kay. As advisors, and since then as colleagues, they have constantly added to my understanding of language, and have also been frequent sources of moral support and constructive criticism. Among my other teachers at Berkeley, James Matisoff first developed my interest in historical semantics, and Yakov Malkiel and Johanna Nichols gave much insightful commentary on earlier versions of this work. I would also like to thank Elizabeth Closs Traugott for her encouragement, criticism, and the inspiration provided by her work.

Numerous colleagues have given me the benefits of their experience and knowledge in commenting on various parts of this book. I have tried to implement much of their advice, and apologize for any instances where the work has suffered from my refusal to heed them. Chapter 2 has profited from the comments of Gary Holland, Dwight Bolinger, Eric Hamp, Tom Walsh, and Calvert Watkins. For comments on chapter 3 I am indebted to Dwight Bolinger, Julian Boyd, Gilles Fauconnier, Suzanne Fleischman, Julie Gerhardt, Mark Johnson, Annette Karmiloff-Smith, Robin Tolmach Lakoff, Iskendir Savasir, John Searle, Dan Slobin, and Leonard Talmy. Robin Lakoff and Don Forman have both been influential in the development of my understanding of conjunction, as represented in chapters 4 and 5; Jeanne Van Oosten's work on topicality was also helpful in chapter 5. And thanks to the Fulbright Foundation, my Polish colleague Barbara Dancygier has engaged me in a very productive dialogue on the subject of conditionals.