However, this type of method is not devoid of inconvenience in sociology. It does not consider the necessary succession of the various phases in the social evolution: it seems on the contrary to consider them all as simultaneous. Consequently, it prevents us from seeing the filiation of social forms. It also runs the risk of falsifying the analysis of the cases which are observed, and of causing simple secondary factors to be taken for main causes. This is what happened to Montesquieu who compared indifferently the cities of antiquity, the France of the Middle Ages, the England of the XVIII. century, the republic of Venice, the government of Byzantium, the Empire of the Sultan, and that of the Shah of Persia. So the comparative method is only an auxiliary process in sociology. Like observation and experiment, it has to be made subordinate to a rational conception of the evolution of humanity. The latter in turn depends upon the use of an original method of observation, belonging to social phenomena, and free from the dangers presented by the preceding ones. This specific sociological method, this “transcendent” process, by which the positive method is completed, is, says Comte, the historical method.[244] IV. Sociology is an abstract science: history, which is its essential method, cannot therefore be history merely considered as a narrative. There are two ways of conceiving history, the one abstract and the other concrete. The latter dominates in the historical works written up to the present time. Their end is to relate and to array in chronological order a certain sequence of events. Undoubtedly in the XVIII. century efforts were made to co-ordinate political phenomena and to determine their filiation. But for all that this kind of work has not ceased to be descriptive and literary. The other form of history, which does not exist up to the present, has for its end the research of the laws which regulate the social development of the human species.[245]