In 2014 Johns Hopkins Press editor Vince Burke suggested to me an intriguing idea for a unique book on the history of American mathematics. He proposed that I scan the history of the nation, and for each decade find an event of mathematical significance. The wider history of the decade (social, political, economic, military) could then be spun out from this mathematical episode. The book would consist of a series of decade by decade chapters. Vince envisioned this book to be welcoming to the general reader, not a dense scholarly monograph.

I found an ideal mix of constraint and freedom in working on a book that had been suggested by someone else. Right from the beginning there was a structure to my efforts that kept me from aimless wandering. But if it didn’t work out, well, it wasn’t *my* idea. I could it blame it on Vince and walk away without regrets. Initially I could view the task as a mere technical exercise in historical research: let’s see what can be said about American mathematics in the 1830s, the 1840s, the 1850s, etc. I must admit, however, that at some point I became fully invested in the project, making it impossible to blithely walk away. And certainly that personal investment was crucial to completing the book.

In making the book my own I found myself transforming it in various ways. Vince had proposed fifteen chapters; I quickly expanded to twenty. More fundamentally, the chapters became short biographies of one individual, or in a few cases two linked individuals. I retained the notion of beginning with an event in a particular decade, but rather than focusing tightly on that ten-year span, I ranged freely backwards and forwards in order to tell the biographical story. Moreover, I did not insist that the instigating event be overtly mathematical, only that the individual involved in the event have a significant relation to mathematics at some point in their life. This gave me more choice of dramatic moments with which to begin each chapter, while retaining a semblance of chronological flow to the whole book, permitting me to claim that I was in some sense covering the whole of the nation’s history. I was still able to weave in the larger historical context that had been such a key aspect of Vince’s original conception, but I now did this within the biographical structures I was creating. In some cases, I rejected potential biographical subjects from the book because I could not figure out how to bring in enough historical detail in a natural way, without awkward transitions: “Meanwhile, the nation was industrializing …”

Vince was fully supportive when he saw the direction I was inclined to take the book. He was a sharp critic when he detected threats to readability, but at no time did he ever say anything like “that’s not what I had in mind.”

Making the book into a sequence of biographical vignettes had the valuable effect of playing to my strengths as a historian. My 1998 PhD dissertation at Hopkins, in the history of science, had been heavily weighted with biographical details of mathematical Americans, mainly from the late nineteenth and early twentieth centuries. Some of this material would directly support several chapters in the book. For more recent years I was able to mine the oral history interviews I had done in the early 2000s for the National Council of Teachers of Mathematics. Aiming at a general readership, as Vince had insisted, led me to treat mathematical concepts gently and concisely. These mathematical passages may be opaque, but they are not, I firmly believe, intimidating. I also felt free, as I would not have in a more specialized academic book, to bring in miscellaneous bits of my background knowledge and interests, accumulated over a lifetime: my youthful fascination with the Civil War; my love of challenging literature, from Laurence Sterne to Thomas Pynchon; my curiosity about my grandfather’s PhD advisor, E. B. Wilson.

Although I encountered moments of frustration, the overall experience of writing *Republic of Numbers* was enormously pleasurable. I hope that some of this pleasure conveys to readers, as they get a glimpse of the rich variety of ways in which Americans have participated in mathematics. I further hope that the book will humanize mathematics for readers interested in history but knowing little mathematics. And for those already interested in the subject, I hope that the book will demonstrate to them how thoroughly mathematics is entwined with the ongoing complications of history.

**David Lindsay Roberts** is an adjunct professor of mathematics at Prince George's Community College. He is the author of *Republic of Numbers: Unexpected Stories of Mathematical Americans through History* and *American Mathematicians as Educators, 1893–1923: Historical Roots of the "Math Wars."*