天生地養，禱祀地神，出於人類酬因的心態。但「地神」的觀念，在長期的歷史演變中，以史料看，大抵分裂為兩大系列：其一為司掌國土、鄉土、代表部分土地的「社」神；其二為代表整個大地與皇天相對的「地神」；這兩者皆稱之為「后土」。做為司掌國土鄉土的社神，其名稱有「后土」、「社」、「土公」、「土神」。做為代表大地的地神，其名稱有土皇、后土、后土皇地祇、地母等等。掌國土、鄉里的土地神，其神格顯然遠較代表大地與皇天相對的地神小；兩者的衍變也各有差別。本文即在論述后土信伶，及其神格之衍變。

People believe that the god of sky gives birth to all things on earth, and the god of earth, and the god of earth raises them. This belief comes from human’s reward psychology. But in long-term historical development, the idea of “the god of earth” has split into two systems. The first system is “the god of ‘社’ “（社神）, in charge of soil and the country’s territory. The second system is “the god of ‘地’”（地神）(the god of all the ground), in opposition to the god of sky. Both of them are called “hou-tu（后土）”. When the god of earth as the god of the country’s territory, people call the god “后土”,”社”,”土公”,”土神”. And when the god of earth as a representation of earth, and in opposition to the god of sky, people call the god “土皇”, “后土”,”后土皇地祇”,”地母”, etc. in the gods system of Taoism, the level of “the god of ‘社’（社神）”is lower than “the god of ‘地’. The author of this article wants to argue the belief of “the god of earth”, and the two split god systems.