A symbol for what is not there, an emptiness that increases any number it's added to, an inexhaustible and indispensable paradox. As we welcome the new millennium, zero is once again making its presence felt. Nothing itself, it makes possible a myriad of calculations. Indeed, without zeromathematics as we know it would not exist. And without mathematics our understanding of the universe would be vastly impoverished. But where did this nothing, this hollow circle, come from? Who created it? And what, exactly, does it mean? Robert Kaplan's The Nothing That Is: A Natural History of Zero begins as a mystery story, taking us back to Sumerian times, then to Greece and India, piecing together the way the idea of a symbol for nothing evolved. For Kaplan, the history of zero is a lens for looking not only into theevolution of mathematics but into very nature of human thought. He points out how the history of mathematics is a process of recursive abstraction: how once a symbol is created to represent an idea, that symbol itself gives rise to new operations that in turn lead to new ideas. The beauty ofmathematics is that even though we invent it, we seem to be discovering something that already exists. The joy of that discovery shines from Kaplan's pages, as he ranges from Archimedes to Einstein, making fascinating connections between mathematical insights from every age and culture.