A number of people helped me with the writing of this book. The most significant contributions came from Professors Rafaella Franci of the University of Siena, Jeffrey Oaks of Indianapolis University, and Barnabas Hughes of California State University at Northridge, who each read the entire manuscript at various stages of development and provided valuable feedback. As a mathematician not well versed in the history of the subject, I found their input invaluable. I also benefited enormously from an e-mail exchange with, and later a visit to, Judith Sigler Fell, the widow of the mathematician who translated Liber abbaci from Latin to English.
My colleague Professor Franco Montagna of the University of Siena provided me with the initial introduction to Professor Franci, and a lengthy conversation with her and her colleague Professor Paolo Pagli early in the project helped orient my research. Likewise, a conversation with Professor Giulo Barozzi of the University of Bologna also provided me a valuable initial overview of the task that faced me in trying to piece together the story of Leonardo’s life and work. Professor Greg Adams of the Mathematics Department of Bucknell University originally outlined the history of Laurence Sigler’s English translation of Liber abbaci and put me in touch with his widow. Serena Ferrando of Stanford University provided an English translation of one particularly important Italian source (Franci’s seminal article, described in chapter 8) for which I did not trust my own translation ability. Christine Holmes of the San Jose State University Library provided considerable assistance and support in conducting my researches in Italy.
Finally, I want to thank my literary agent, Ted Weinstein, who is always an enthusiastic and solid supporter of my efforts, and who consistently goes the extra mile to find the perfect publisher for my work, and George Gibson, my publisher at Walker & Company, who contributed significantly to the final form of the narrative.