John Nelson Darby expounds on 1 Corinthians 9, emphasizing the nature of ministry and the responsibilities of preachers. He highlights Paul's refusal to exercise his rights as an apostle for the sake of the gospel, illustrating the importance of serving without seeking personal gain. Darby discusses the balance between being supported by the church and maintaining independence in ministry, stressing that preachers are ultimately accountable to God. He warns against the dangers of legalism and the necessity of living a life consistent with one's preaching to avoid being a 'castaway.' The sermon concludes with a call to uphold the integrity of the gospel while navigating the complexities of ministry.