We start at the very outset with an implied assumption; for by “sequence,” Schurtz distinctly understood an ordered sequence. His work is primarily an attempt to determine what this ordered sequence has been, and how it has been determined. The norm of organization in which the human race expressed itself primarily, is, according to him, the age-group. Owing to the historical development of various cultural areas, it is no longer possible to detect this “primary element;” and he consequently finds it necessary to demonstrate its existence from another point of view, which is essentially psychological. The development of the age-group has followed a very definite sequence—definite, because it has been determined by certain inherent tendencies of the human mind. These tendencies are “the instinct for association”[15] (_Geselligkeitstrieb_) and “the sexual instinct” (_Geschlechtstrieb_). Granting the existence of these two tendencies, we have then to inquire how they have conditioned the essential similarities in the evolution of our social life, and the forms in which that social life has expressed itself. There are two possible assumptions. We may assume that at a certain stage of cultural development groups of people possessed no social individuality sufficiently strong to determine their own development, and that the _Geselligkeitstrieb_ and _Geschlechtstrieb_ alone, or reinforced by other factors, were sufficiently strong to condition development along certain lines; or we may, on the other hand, assume that the primary modes in which people have expressed themselves are necessarily of so simple and generalized a type, that they always were the same. Schurtz has practically assumed a stage in human development when the individuality of the component units of a social group was at a minimum; when there was, so to say, a “group mind,” whose initial development is most easily explained by the influence of inherent tendencies. It must be said, in fairness to Schurtz, that the other alternative mentioned above was probably also in his mind. However, he seems to have elaborated his theory with the first alternative constantly before his eyes. This unexpressed assumption is of the greatest possible moment in Schurtz’s interpretation, because it immediately establishes a certain fixity for his primary norm; and excluding as it does the possibility of variation, because the two tendencies, as constants, are acting upon social groups whose component members have a minimum of individuality, brings it about that the same primary norm must be simple and generalized in its nature. Schurtz has thus given us a psychological _milieu_, and we must now proceed to investigate what are the specific norms of development, the method by which these norms have been determined, the nature of their sequence, and how this sequence has been absolutely conditioned. The first two of these points become clearer if we attack the question of sequence first.