1 Corinthians 2:9-16
Vs. 9 becomes both the concluding thought to the first section of ch. 2, and the pivot point into the second section of ch. 2. As Paul noted elsewhere, his writing was well-known to be better than his speaking, and he actually demonstrates a mastery of literary style and function in his epistles. So here he uses the OT citation from Isaiah 64 to begin a new section and concept, focusing on the empowering work of the Holy Spirit in the ministry of the Christian. The work of the Holy Spirit is essential for anyone to understand the good plan of God.