A significant influence of Hume’s political philosophy lies in his developing a foundation based on passions and human nature for men’s political and moral spheres, in the trend of secularization that characterized the Age of Enlightenment. In this philosophical project known as ethical naturalism, although Hume is famous for treating reason as subordinate to the passions, his elaboration of the passions as found in the second book of the Treatise has long been undervalued by Hume scholars.