"The flax" is a fairy tale written by Hans Christian Andersen. In this story Andersen shows how important positive thinking is for us to overcome the adversities that life imposes and that it is necessary to always have this type of thinking in our lives even though the world and other people around us try to take it away from us.
For this reason, we can consider that a selection entitled "The flax" would keep the importance of positivity as a theme.
I don't know much about the Sydney mines, but from the context, I can infer that the tunnels were unsafe. Whether being that they were collapsing, or they were filled with poisonous gasses.
