This book by Anthony Grafton explores the life and career of Girolamo Cardano, an Italian doctor, natural philosopher, mathematician, and astrologer of the Renaissance era. Grafton delves into the principles and practices of astrology during this time, showing how Cardano and his contemporaries adapted the ancient art for publication and marketing in a new era of print media and changing science. The book also maps the context of market and human forces that shaped Cardano’s practices and kept him at the top of a world rife with patronage, politics, and vengeful rivals. Overall, Grafton argues that Cardano’s astrology was a profoundly empirical and highly influential art, one that was integral to the attempts of sixteenth-century scholars to understand their universe and themselves.