Simon Flexner was the famous medical investigator, discoverer of the "Flexner vacillus" and the "Flexner serum", who became the creating director of the Rockefeller Institute for Medical Research (now Rockefeller University) and, eventually, the acknowledged leader of American medical science. The Kentucky-born son of impoverished German Jewish immigrants, he grew up in penury. As he never completed the eighth grade, he was almost completely self-educated...