The many published volumes of the writings of Harold Adams Innis testify to his extraordinary grasp of the ordering principles of human history. The notes that he left at the time of his death provide a new and revealing profile of the inner workings of this restless and relentless mind. Innis maintained, added to, and corrected, in the last seven years of his life, a single system of cross-referenced notes, which came to be called the Idea...