 Soon after finishing the Course, Comte returned to his initial project and began outlining the System of Positive Polity. The Discourse on the Positive Spirit, which had served as the preface to the Philosophical Treatise on Popular Astronomy (1844), had already emphasized the social purpose of positivism and its aptitude to replace theology in politics and morality. But his encounter with Clotilde de Vaux would turn his life upside down and give Comte’s second career an unexpected twist (1845–1846).