Mandelbrot's book belongs in the category of "Buy two copies, so you'll have one to lend to friends". This book makes the compelling case that, for everything we think we know about complex finance and stock market theory, reality is driven by overlapping patterns and interrelated events that behave as though they are in powerful echo chambers. Mandelbrot is best known by the public for the Mandelbrot Set, an infinitely-complex mathematical curve that's really quite beautiful. But the infinite complexity illustrated by the curve is also at work in market behaviors, which is why, for instance, the same stock curve looks the same at the hourly, daily, weekly, monthly, and annual levels -- no matter what level of zoom, most stock prices bounce and gyrate over great magnitudes. To anyone who enjoyed the advent of chaos theory in the public consciousness around 1992 or 1993, Mandelbrot's book will make an inordinate amount of practical sense in the financial world.