“ In the early 1860s, Oliver Wendell Holmes Jr., then a brash Harvard undergraduate, wrote an essay criticizing Plato, whose classifications of ideas he found ”loose and unscientific.” Holmes sent a copy of the essay to Emerson, whose books, he later said, had ”set me on fire.” He soon received in return a nugget of stern wisdom. ”I have read your piece,” Emerson replied. ”When you strike at a king you must kill him. ”