On the substance of this development there is one observation which inevitably suggests itself to any critic who approaches the problem from the philosophical side. Necessarily, as the relation of the individual to society is the root of every social problem, psychological sociology consists to a great extent in exercises upon the theme of identity and difference. These exercises have hitherto been for the most part unconscious and involuntary. And the high degree of substantial truth which is attained by inquirers who have not thought the logic of identity worthy of a single glance, is the strongest possible confirmation of the common experience that it is safer to neglect theory than to be careless of facts. Nevertheless, it has now become apparent, that a point has been attained at which logical criticism is absolutely essential, or if not logical criticism, at least some reference to the familiar and well-established results of ancient or modern social philosophy. For it is a universal characteristic of the {46} sociological movement before us, that identity and difference are referred to different spheres, and the “one” and the “other” are regarded as reciprocally exclusive atoms. [1] The difficulties and fallacies which thus arise are innumerable. Thus we have the contagious common feeling of a crowd [2] taken as the true type of a collective mind, obviously because it is not understood how an identical structure can include the differences, the rational distinctions and relations, which really constitute the working mind of any society. So again we have one type of law marked off as corresponding to social similitude, [3] while a different type corresponds to the social division of labour; simply because the category of resemblance has been substituted for that of identity, and is treated as exclusive of differentiation; with the result of a really terrible distortion of facts in the attempt to separate the whole sphere of penal enactment from that which deals with industrial organisation. So with the entire set of notions of “Imitation,” “Repetition” and “Invention.” [4] The separation of Imitation and Invention is simply the popular exclusion of Difference from Identity; while the treatment of Repetition as the characteristic of knowable phenomena and the mode of utterance of social Imitation means the restriction of rational Identity to its barest form, and the exclusion from {47} social theory of absolutely every case of true cooperative structure. For true cooperative structure is never characterised by repetition, but always by identity in difference; it is the relation not of a screw to an exactly similar screw, but of the screw to the nut into which it fastens.