Who is Chu Wen from Gladys Aylward: The Little Woman and what is their importance?

Chu En is an orphan under Glady's care. When he becomes old enough to strike on his own, Chu insists that God has told him he must go to Yangcheng, even though it is a dangerous and devastated place. His only request is that Gladys will pray for a stethoscope for him. Chu uses the stethoscope to administer to the people of Yangcheng, both physically and spiritually.