D.L. Moody emphasizes the necessity of being filled with the Holy Spirit for effective service, arguing that many Christians today live beneath their privileges by not seeking this power. He reflects on the experiences of the Apostles, who, despite having the Holy Spirit, were commanded to wait for a special endowment of power before embarking on their mission. Moody challenges believers to examine their readiness to be used by God and to actively seek the Holy Spirit's empowerment for witnessing and ministry. He asserts that true effectiveness in spreading the Gospel requires supernatural power, which is available to all who earnestly seek it. Ultimately, he calls for a commitment to be ready to go wherever God leads, filled with the Spirit to bear fruit for His kingdom.