In On the Spirit and the Letter, St. Augustine responds to Tribune Marcellinus, who expressed surprise at the claim that man could live sinlessly with divine assistance. Marcellinus questioned how something could be deemed possible if there are no examples to prove it. Augustine passionately defends the concept of grace, illustrating that while the law is good and holy, it alone cannot save us; it often amplifies our guilt when we know our duties but lack the ability to fulfill them. He emphasizes the necessity of the Spirit’s support, which fills our hearts with grace, enabling us to love and accomplish the good that is commanded of us. This profound exploration not only clarifies the Apostles message, The letter killeth, but the Spirit giveth life, but also offers insights into the divine assistance we receive to pursue righteousness. - Summary by Claude Fleury in The Ecclesiastical History