Polio was one of the scourges of the 20th century. And it mainly struck children. All of a sudden a person contracted polio and suffered terribly for several days; sometimes they recovered, sometimes they died, and sometimes they were left permanently disabled. The most famous polio victim of all time, Franklin Roosevelt, hid his disability from the public. But this story has a true hero: Jonas Salk, who developed a vaccine which led to the almost complete eradication of this dreaded disease. And Dr. Salk never patented the vaccine or earned any money from his discovery.