"The big horse," in racing vernacular, is the animal that brings fame and fortune to a stable. He's the heavyweight champion, the All-American quarterback, the four-legged Michael Jordan of the barn. Seabiscuit was once Tom Smith's "big horse." A generation ago, Secretariat was Lucien Lauren's. In 2003, Funny Cide was Barclay Tagg's. In sixty years as a trainer, P. G. Johnson had never had one -- until Volponi.
P. G. Johnson was a blue-collar wizard, a hardscrabble tough guy who had come east from Chicago, determined to make his mark on New York. And he did. He became leading trainer at...