Who is the rock and who is the river? What does Sam decide to do at the end of the book?

Sam and Stick have had discussions about the "rock and the river", and Leroy and Sam discuss it again after Stick's death. The analogy is that some people are like a rock while others are like the river. Each tends to see the lives of the other and sometimes wish they could change. The rock remains stationary without ever seeing what lies beyond the next bend of the river. The rock is strong and stable but sometimes wonders what lies beyond. The river knows what lies beyond and is alway always moving, filled with turmoil and rage, but sometimes looks at the stability of the rock.

At the end of the novel, Sam decides to continue his work with the Black Panthers, but he also determines that he will go home to be with his parents and continue school as usual.