What is left...#leaving

Metonymy is best defined as a figure of speech in which

Arrange the events in chinese history in chronological order using the numbers 1-4. the ming dynasty falls to the qing. china experiences a 400-year period of peace known as the pax sinica during the han dynasty. a golden age of expansion and culture occurs during the tang dynasty. nationalists and communists fight a civil war for control of china.

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?