It was meant to be a pleasant weekend of relaxation on the shores of Lake Michigan, north of Chicago, for Donald Liu, his wife, and their three children. But that abruptly changed on the windy morning of Sunday 5 August when Liu saw two 12 year old boys in choppy, deep waters without life jackets and struggling to stay afloat. Liu was faced with a life or death decision: he could remain on shore and wait for rescue crews, or he could enter the dangerous waters himself and try to save the boys.

Liu was well acquainted with life and death decisions. As section chief of pediatric surgery and surgeon in chief at the University of Chicago Medicine Comer Children’s Hospital, he made them almost every day. An internationally recognized expert in minimally invasive pediatric surgery and the surgical treatment of intestinal disease, Liu had …