Carlo Cattaneo was one of the most prominent Italian intellectuals of the nineteenth century. Known for his prominent role in the Five Days of Milan uprising in 1848, he combined a vivid intelligence with a reform-oriented mind and a strong civic passion. This volume offers an exhaustive selection of Cattaneo’s writings, which cover a wide range of issues and advance highly innovative theories, such as the achievement of republican federalism in Italy and Europe, thought as a principle of political economy, and the psychology of associated mind. The two introductory essays examine how his ideas developed through the time and argue for their enduring vitality