PROCESSES OF HISTORY
some members of this supreme race. Conversely, wherever the brachycephalic (or short-headed) races have made their appearance, decadence has straightway followed; nor do the advocates of this thorough-going conception shrink from the conclusion that progress in the future must depend upon the increased propagation and the physical dominance of the long-headed variety.
An equally positive, though perhaps less animating theory places the emphasis, in seeking to account for the differences of human groups, not on the physical, but on the mental characteristics of races, and from this root has grown the extensive literature of "race psychology." According to this view, the part played in history by any aggregation of men is a direct reflection of its collective character and mentality. The subject and method of this psychology, initiated by Wilhelm von Humboldt, seems first to have been cultivated by Steinthal and Lazarus, but owes its vogue, apparently, to men like Mommsen and Renan. While the interest enlisted by the summary descriptions of the psychology of peoples has been widely extended, the explanation afforded by the procedure is not illuminating, for it consists merely in saying that events and insti-
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