The Marrow is the historically important book that caused the Marrow Controversy in the Church of Scotland. The Marrow is written as a dialogue among a pastor, a legalist, an antinomian, and a neophyte Christian. It advocates a free grace gospel against both a works-righteousness gospel and a cheap-grace gospel. At the time that Boston's edition came out (circa 1720), the Moderate Party dominated the Church of Scotland, and advocated a legalistic...