Beccaria's manifesto against cruel punishment and abuse of power spread through Europe like a wildfire and inspired radical reforms of repressive and coercive institutions throughout the continent. But what made Beccaria’s tract so popular with enlightenment rulers and thinkers? My hypothesis is that Beccaria managed to offer a vision of radical reforms that would follow a rational, and moderate, path. It pleased Les Philosophes and the administrators in equal measure. Its novelty resided in the criticism of criminal law from the viewpoint of those who were immediately affected, rather than from the viewpoint of the lawyers. It was a Copernican revolution in perspective and one that stood with the many against the few privileged ones. There are two key insights in Beccaria’s political theory of criminal justice. Firstly, the law should not be an instrument of oppression but rather a tool to foster life in common. Secondly, to constrain the abuse of political power every political system needs constitutional guarantees that minimize the interference of criminal law in people’s lives and promote social welfare policies so as to prevent crime.