The setting of the story illustrates growing up in the company of men without the support of women. Life is hard, the climate is cold, and growing up is hard. The men are isolated because they are without their families, outside support, and for Stephen, the first time without motherly care and love.
Nowlan's creation of the setting is one of realism... many men lived this way on a regular basis, and many sons followed in their father's footsteps. The men in the camps only had each other, which is evidenced in the card playing they used to pass the time when they couldn't work. In addition, Stephen's father isn't being harsh with his son, he is making him face reality.
Polack's story about the glass roses is a memory... thinking of his mother, a home, and the fragility of life and glass roses. He doesn't remember them because they shattered, he remembers then because thoughts of his mother are comforting. Stephen is compassionate... and yet, his father seeks to diminish that innate compassion and make a man of him, and yet, Stephen is still young enough to share that compassion with another.