Finishing Flatland, a novella published by British mathematician and teacher Edwin Abbott a good 20 years before Einstein's General Theory of Relativity and the growth of quantum mechanics, leaves the reader wondering what Abbott could possibly have known about these later figures and events. But the book's very existence underscores just how fundamental those 20th century ideas are. The entire premise of Flatland, in fact, is about shaking our perceptions of what we believe to be our own – and only – physical world. Even the popularity of Flatland today is shaped by the changes in our worldly perceptions since 1884.