Samuel Logan Brengle emphasizes that while many desire to be used by God, they must first ensure they are humble, teachable, and sanctified for His service. He compares God's search for usable individuals to a merchant seeking qualified employees, highlighting that God looks for those whose hearts are perfect toward Him rather than those with great abilities. Brengle encourages believers to examine their own hearts and to trust in God's process of preparation, using the example of Paul, whose faithfulness led to immense impact despite his trials. Ultimately, he reassures the troubled that their perceived uselessness may not reflect their true value in God's eyes, urging them to be filled with the Spirit to flow rivers of holy influence. The message concludes with a promise of reward for those who faithfully serve God.