day after day in such manner as to be able to draw at any given moment a general conclusion from these highly complicated and ever changing factors, factors of which the most important often work for a long time under cover before they suddenly and forcibly come to the surface. A clear survey of the economic history of a given period can never be gained at the time; it is possible only later, after the subsequent collection and assortment of the material. Here statistics are an indispensable aid, but they always limp behind the event. When dealing with current contemporary history one will often be forced to treat this, the most decisive factor, as constant and to consider the economic situation found at the beginning of a given period as governing the entire period without variation, or to consider only such changes of the situation as emanate from events plainly visible and therefore also quite manifest. The materialist method must here too often confine itself to a tracing back of political conflicts to the conflicts of interests among the social classes and class factions of a given economic development, and to prove that the different political parties are the more or less adequate political expression of these same classes and class factions.
It goes without saying that the inevitable neglect of the simultaneous changes of the economic situation, the real basis of all the events to be investigated, is bound to be a source of error. But all the conditions of a comprehensive presentation of the history of the
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