A death row prisoner
The black believer calls the white professor a death row prisoner to metaphorically explain his situation and his wish to end his life. He was a prisoner of his own life, meaning that there was something that was keeping him imprisoned the lack of empathy or the will to see the reason to live.
The sun don't shine the same way every day
In his attempt to change the white professor's mind, to keep him from committing suicide, the black believer makes a point that he might be having one of the bad days. He wants to convince him that life isn't sunny and perfect every day and that dark and bad days are just as an important part.
The shadow is you
The black believer tells the white professor that he is the shadow himself; he is the one making his own shadow, refusing to look past it to see the light. A man is most often his own worst enemy that keeps himself from finding happiness.
