What does Elroy Berdahl do that leads O’Brien to call him “the hero of my life?”

1) each morning , dew glistens on the grass. 2) the sun yawns , scanning the horizon for companion clouds. 3) perched high ancient oak trees, startlings and sparrows announce a new day.

How can you tell that the text is from a biography

London includes a quote about john thornton as he is observing hal attempt to motivate the exhausted dogs "it was idle, he knew, to get between a fool and his folly". if the word "idle" is defined as "of no real worth, importance, or significance", what does this statement mean with regard to hal? who is the fool? what is hal's folly? why would john thornton think it of no real worth or useless to intervene?