Humans are pattern-matching creatures, and astrology is the universe's grandest pattern-matching game. In this refreshing work of history and analysis, data scientist Alexander Boxer examines classical texts on astrology to expose its underlying scientific and mathematical framework. Thousands of years ago, astrologers became the first to stumble upon the powerful storytelling possibilities inherent in numerical data. To correlate the configurations of the cosmos with our day-to-day lives, astrologers relied upon a "scheme of heaven," or horoscope, showing the precise configuration of the planets at a particular instant in time as viewed from a particular place on Earth. Although recognized as pseudoscience today, horoscopes were once considered a cutting-edge scientific tool. Boxer teaches us how to read these esoteric charts-and appreciate the complex astronomical calculations needed to generate them-by diagramming how the heavens appeared at important moments in astrology's history. He then puts these horoscopes to the test using modern data sets and statistical science, arguing that today's data scientists do work similar to astrologers of yore. By looking back at the algorithms of ancient astrology, he suggests, we can better recognize the patterns that are timeless characteristics of our own pattern-matching tendencies.