 Lipsius’s lifelong project was to transform contemporary moral philosophy through a new reading of the Roman Stoic philosopher Seneca, while also revitalizing contemporary political practice by drawing on the insights provided by the Roman historian Tacitus. Before publishing his major edition of Seneca’s philosophical writings in the year before his death, he wrote two theoretical treatises on Stoicism, which provided the philosophical foundation for a new interpretation of Seneca and a new understanding of Stoic doctrines.