D.L. Moody emphasizes the vital role of the Holy Spirit in bringing the teachings of Jesus to our remembrance, highlighting that true power in testimony comes from being filled with the Word of God. He notes that many Christians lack effective testimony and prayer because they do not have the Word hidden in their hearts, which the Spirit can then illuminate. Moody encourages believers to seek the Spirit's guidance to speak with authority and to be channels of God's blessings. He reminds us that while we may not fully comprehend the wonders of Heaven, the Spirit reveals these truths to us, deepening our understanding of God's promises.