This series of papers was begun in March, 1888. A single number was printed, when it was interrupted the course of events, and not resumed until nearly years later, in January, 1890. The plan of the series was not formed in my mind when I wrote the number. In returning to my task I found that my original plan had shaped itself in the underground laboratory of my thought so that some changes had to be made in what I had written. As I proceeded, the...