There are objective reasons as well as subjective reasons. The objective reason is that the objectivity or materiality in the field of social history is much more complicated than that in nature. For example, social system, social relations between people (except ideological relations) and people's practical activities are all objective or fundamentally objective realities, but these are intangible and can only be grasped through thinking, not through feeling like natural substances. It is more difficult to explore the motive force of social development, because "history is only an activity that people pursue their own goals", so on the surface, history is driven by people's will. The subjective reason is that the material understood by metaphysical materialism is limited to nature, and because of the complexity of social and historical fields, metaphysical materialism also understands the motive force of historical development as the power of spirit or will, thus falling into idealism in the view of history, and the historical field becomes the "last refuge" of idealism. The birth of Marxism and the establishment of historical materialism drove idealism out of the "last refuge". Lenin said that the idealistic view of history has two major defects: first, it only studies people's ideological motives without exploring the material motives and economic roots behind them; The second is not to recognize the decisive role of the people in creating history. On the first point, people's ideological motivation is restricted by material and economic conditions, such as buying a house by wallet, landing on the moon by various conditions and so on. Regarding the second point, before the birth of Marxism, no one fundamentally affirmed the role of the people in creating history.