T. Austin-Sparks emphasizes the significance of God's starting point for experiencing heavenly fullness, illustrated through the lives of Elijah and Elisha. He explains that true spiritual progress begins with recognizing our weakness and dependence on God, as exemplified by Elijah's journey from despair to divine purpose. Sparks highlights that while many seek to advance without returning to God's foundation, they risk spiritual limitation. The sermon calls for a deep act of faith and acceptance of God's position, leading to a progressive outworking of His will in our lives. Ultimately, it is through acknowledging our emptiness that we can access the fullness of life found in Christ.