“一二三”是中国哲学普遍的发展路径。本文试图论述在孟子哲学中“一二三”发展路径的构建是可能的:首先通过自然性向道德性过渡而出现的作为本体的“仁”便是“一”的确立;其次通过把“仁”放在历史中与情感中的考察,贯通了理论与现实、理性与感性这两组对待关系,从而展开了“二”;最后通过在具体的道德实践中的权变,丰富完善了作为“中道”的“三”。 “One Two Three” is a common development path of Chinese philosophy. This article tries to discuss that it is possible to construct the “One, Two, Three” development path in Mencius philosophy. Firstly, the “Ren” as the noumenon which appears through the transition from nature to morality is the establishment of “One” Secondly, through investigation of “Ren” in history and emotion, through the treatment of relationship between theory and reality, rationality and sensibility, we expand the “two ”; Finally, through the concrete moral practice The contingency, enriched and perfected as the “middle” “three ”.