Ferguson uses the Marrow Controversy that occurred in the Scottish Presbyterian church during the early 18th century to illuminate and provide an excellent theological treatment on the classic issue of the relationship between law and gospel and their role in the life of the believer. This means he provides an analysis of subjects like legalism, antinomianism, and assurance. In some ways, you might think of this book as a deep dive into the topic “the gospel in the life of the believer” conducted through the lens of a particular historical case study. Ferguson’s treatment is both theologically astute and pastorally sensitive and applicable. This is one of those books I feel like I will want to return to and read again in years to come to refresh myself in the aid it supplies.