A groundbreaking look at how the science of complex systems is changing economics. Economics has for decades claimed that the economy is a rational, stable, efficient machine, governed by well-understood laws. Mathematician David Orrell traces the history of this idea from ancient Greece to the financial centres of London and New York, showing exactly how it is mistaken - and then brilliantly illustrates how new ideas in mathematics, psychology, and environmentalism are helping to reinvent economics for the 21st century.