In late 1947, William Larimer Mellon Jr., scion of the Pittsburgh Mellons, was rich and 37, with a pretty wife and children and a new house on a smooth-running Arizona ranch. He was looking through the pages of LIFE one day when he stopped at a picture story about Dr. Albert Schweitzer, who 51 years ago gave up a brilliantly versatile career−as theologian, organist, teacher and musicologist−to become a doctor and work among the natives in the African jungle. "There was a picture of Dr. Schweitzer and an antelope," Mellon recalls. "I had thought he was an organist."
Gradually a...