I have a personal theory that every lesson is, at root, about at least one member of the Godhead. Some focus more on Christ, some focus more on Heavenly Father, and some focus more on the Holy Ghost. By my interpretation the star of this lesson is the Holy Ghost. Right out of the gate the manual points out that
“True to His [where His=Jesus'] word, He continued to guide them from heaven. He sent the Holy Ghost to be a comforter and a revelator to them.”
The church of Christ was only able to exist without him on the earth because of the Holy Ghost. And I would assert that the apostasy is ultimately caused by the loss of the Holy Ghost.