The 1876 United States Centennial Exhibition in Philadelphia was not only the United States' first important world's fair, it signaled significant changes in the very shape of knowledge. Quarrels between participants in the exhibition represented a greater conflict as the world transitioned between two different kinds of modernity--the Enlightenment of the seventeenth and eighteenth centuries to the High Modern period of the nineteenth and twentieth centuries. At the center of this movement was a shift in the perceived relationship between seeing and knowing and in the perception of what...