In "A Treatise on Nature and Grace: Against Pelagius," St. Augustine explores the depths of theological concepts surrounding human nature, divine grace, and the human will. Set against the contentious Pelagian controversy, Augustine embarks on a detailed refutation of Pelagius's views, underscoring the profound corruption of human nature by sin and the indispensable need for divine grace to achieve salvation and restoration. Augustine firmly holds that human nature, though initially pristine and complete, succumbed to corruption, rendering it impotent in reclaiming its original righteousness without God's intervention. He robustly contests the Pelagian assertion of human nature's capacity to attain righteousness independently, asserting instead that humanity's redemption from God's righteous wrath is solely through Christ's grace—a grace that is freely given, not earned. Addressing the misinterpretations of scripture by Pelagius, particularly regarding sin's nature and human nature's ability to eschew sin, Augustine clarifies the profound corruption sin introduces, necessitating divine grace for genuine healing and redemption. He distinguishes God's righteousness, which transcends mere law adherence and is realized through the acceptance of Christ's grace, leading to a righteousness beyond human attainment. The treatise provides a nuanced exploration of the human struggle against sin, discussing various sin types and the need for God's grace in overcoming them. Augustine acknowledges the role of human will in resisting sin but maintains that it's ultimately inadequate without God's empowering grace. This seminal work is a cornerstone of theological thought, offering profound insights into the nature of sin, grace, and human redemption.