Simon Flexner pioneered in field investigations where infectious diseases were potentially epidemic. He discovered the Flexner bacillus, the cause of a common form of dysentery, and the Flexner serum for treating meningitis . His research expertise was already legend when he was selected as the organizing director of the Rockefeller Institute for Medical Research in New York City. For thirty-five years he cultivated the spirit and guided the work of the new institute, while implementing John D. Rockefeller's vision of bringing medicine into the realm of science.

Flexner, the fourth of nine children, was born in Louisville, Kentucky, on March 25, 1863, to Jewish immigrants. His father, Morris, emigrated from Bavaria, first to Strasbourg, France, where he taught school, then eventually to Louisville. He became a peddler and eventually a wholesale merchant of dry goods. Flexner's mother, Esther Abraham, grew up in Alsace and was a dressmaker in Paris before immigrating...