Octavius Winslow emphasizes the sovereignty and grace of God in his sermon 'Evening Thoughts - March', illustrating how God's mercy is bestowed according to His divine will, independent of human merit. He encourages believers to recognize their election and the transformative work of the Holy Spirit, which leads to sanctification and a deeper understanding of God's love. Winslow highlights the importance of humility and reliance on God's grace, urging Christians to embrace their identity as chosen vessels of His mercy. He reassures the faithful that their struggles and afflictions are shared by Christ, who sympathizes with their suffering and guides them through life's trials.