By " nervous or igins" are meant the fundamental nervous conditions and processes that are the sources from which have evolved our motives and emotions, sensations and thoughts, conduct and language. They are to be detected, for the most part, by a close comparison of various manifestations of the same kind of activity, by the elimination of differences, and the consequent isolation of a residuum which is common to all of them. Thus, from the comparison of different phases of ambition the fact emerges that they all involve ideas of a success; and we may, therefore, conclude that this idea underlies them all, and is their stimulus.