許孚遠師承唐樞，下啟劉宗周，是甘泉學派中具樞紐地位的思想家。許孚遠受唐樞影響終其一生都篤信性即真心即良知，但同時他又堅持人之性亦即真心不可能不被習氣所障蔽，故提出了「合靈與氣」為心的看法。他不僅以此看法來調停李材與胡直之間的心性之辯，還據此提出了心性「非一非二」亦即心性不離而有別的觀點，他認為學者只要著力於存心復性之工夫，心性便可「非二」。因此，在許孚遠的心性論思想中，有兩種心：即心即性之心與「合靈與氣」之心，這兩種心又實際上與他不同的工夫論系統有其內在關聯。許孚遠的這種心性觀是基於他對陽明學流弊、困境以及出路所做的獨特思考和探索。

As the hub of the Ganquan School, Xu Fuyuan was a student of Tang Shu and a teacher of Liu Zongzhou. Greatly influenced by Tang, Xu stuck throughout his life to the idea of “the nature is the true mind or the conscience”. Meanwhile, he also maintained that people’s nature, i.e., their true mind, could not be obscured by their habits, so he put forward the idea that the mind is the “integration of the nature and qi”. On the basis of this idea, he tried to mediate between Li Cai and Hu Zhi on their debate about what the mind and the nature are, and went further to propose the idea that the mind and the nature are “neither one thing nor two”, that is, they are inseparable but different. In Xu’s view, as long as scholars devote themselves to maintaining their mind while restoring their nature, their mind and nature would not be separated. Therefore, in Xu’s view about the mind and the nature, there are two kinds of “mind”: one that is the nature, the other that integrates the nature and qi. In fact, these two kinds of “mind” are related to the various self-cultivation methods of Xu. These thoughts of Xu Fuyuan were in fact based on his unique reflections and explorations on the shortcomings and dilemmas of Yangming tradition.