Complex sentence: On the advice of a gambler on board the train, Borah decided to settle in Boise, Idaho, for, as his biographer, Marian C. McKenna, put it, "that was as far west as his pocketbook would take him".
Split into simpler sentences: On the advice of a gambler on board the train, Borah decided to settle in Boise, Idaho. Borah's biographer, Marian C. McKenna, said that Boise was "as far west as his pocketbook would take him".