The first postulate is that primitive men were originally assembled in chaotic hordes, and that organized society was developed out of the chaotic mass by the segregation of groups and the differentiation of functions within each group. Now the American aborigines collectively represent a wide range in development, extending from a condition about as primitive as ever observed well toward the verge of feudalism, and thus offer opportunities for testing the postulate; and it has been found that when higher and lower stages representing any portion of the developmental succession are compared, the social organizations of the lower grade are no less definite, perhaps more definite, than those pertaining to the higher grade; so that when the history of demotic growth among the American Indians is traced backward, the organizations are found on the whole to grow more definite, albeit more simple. When the lines of development revealed through research are projected still farther toward their origin, they indicate an initial condition, directly antithetic to the postulated horde, in which the scant population was segregated in small discrete bodies, probably family groups; and that in each of these bodies there was a definite organization, while each group was practically independent of, and probably inimical to, all other groups. The testimony of the observed institutions is corroborated by the testimony of language, which, as clearly shown by Powell,(56) represents progressive combination rather than continued differentiation, a process of involution rather than evolution. It would appear that the original definitely organized groups occasionally met and coalesced, whereby changes in organization were required; that these compound groups occasionally coalesced with other groups, both simple and compound, whereby they were elaborated in structure, always with some loss in definiteness and permanence; and that gradually the groups enlarged by incorporation, while the composite organization grew complex and variable to meet the ever-changing conditions. It would also appear that in some cases the corporeal growth outran the structural or institutional growth, when the bodies—clans, gentes, tribes, or confederacies—split into two or more fragments which continued to grow independently; yet that in general the progress of institutional developmentwent forward through incorporation of peoples and differentiation of institutions. The same process was followed as tribal society passed into national society; and it is the same process which is today exalting national society into world society, and transforming simple civilization into enlightenment. Thus the evoluffon of social organization is from the simple and definite toward the complex and variable; or from the involuntary to the voluntary; or from the environment-shaped to the environment-shaping; or from the biotic to the demotic.