At first when I saw there were three sections, I thought of the three rewards (glories) but then I noticed the vision indicated the middle section was actually the absence of anything .... the middle ground, there was nothing (no one) there any longer, it had all separated, no middle ground, you were either on fire for the Lord, or falling away. It might be that awful gulf or separation between the tree of life and the great spacious building in Lehi's vision.