Matter-Human-Affair 3 Principles´ Harmony: An Empirical Study of the Water-Soil Conservation in Loess Plateau

Earth is actually a system of everything on it and the relationships among them, which could be group into matter, human and affair where principles lie in. The harmony among them is absolutely necessary for the co-sustainability. When dealing with the complex geographic problems, the 3 principles should be all taken into account and the harmony worked for. Herewith the 3 concepts of "Matter -human-affair" principles have been defined and the relationship between the "3 Principles\´ Harmony" and the complex geographical questions discussed. Taking the research of the water-soil conservation in Loess Plateau as an example, the targets and requests of the "3 Principles\´ Harmony" in the research of complex geographic questions have been explained. As the scientific ideas transformed into the philosophic notions, the corresponding relationships between the "principles of matter", "principles of human", "principles of affair" and "as is", "ought to", "to do" have been described; The "3 Principles\´ Harmony" is regarded as the fruitful approach to completing the 3 missions of understanding, determining and reforming the world. The idea and methodology might help integrate natural sciences, social sciences and technologies as well as perceive the 3 principles whilst solving the complex questions.