During the Enlightenment, a now little-known Italian marquis, while in his mid-twenties, wrote a book that was destined to change the world. Published anonymously in 1764 as Dei delitti e delle pene, and quickly translated into French and then into English as On Crimes and Punishments, the runaway bestseller argued against torture, capital punishment, and religious intolerance. Written by Cesare Beccaria (1738-1794), On Crimes and Punishments sought clear and egalitarian laws, better public education, and milder punishments. Translated into all of the major European languages, Beccaria’s book led to the end of the Ancien Régime. In 1774, on the cusp of the Revolutionary War, the Continental Congress explicitly hailed Beccaria as "the celebrated marquis." Called the “Italian Adam Smith,” Cesare Beccaria—like his Italian mentor, Pietro Verri, an economist—wrote about pleasure and pain, economic theory, and maximizing people’s happiness. Once a household name throughout Europe and the Americas, Beccaria taught economics before the appearance of Smith's The Wealth of Nations but died in obscurity after working for decades as a civil servant in Austria’s Habsburg Empire. As a public councilor, Beccaria pushed for social and economic justice, monetary and legal reform, conservation of natural resources, and even inspired France’s adoption of the metric system. In The Celebrated Marquis, award-winning author John Bessler tells the story of the history of economics and of how Beccaria’s ideas shaped the American Declaration of Independence, constitutions and laws around the globe, and the modern world in which we live.