离娄上 · 第 12 / 28 章 · 孟子 4A.12
《孟子·离娄上》4A.12：诚者，天之道；思诚者，人之道
孟子从获于上、信于友、悦于亲，一路追到诚身，指出真正的政治与关系能力最后都要回到‘诚’这个根，不明乎善，就不可能诚其身。
孟子曰：「居下位而不获于上，民不可得而治也。获于上有道，不信于友，弗获于上矣。信于友有道，事亲弗悦，弗信于友矣。悦亲有道，反身不诚，不悦于亲矣。诚身有道，不明乎善，不诚其身矣。是故诚者，天之道也。思诚者，人之道也。至诚而不动者，未之有也。不诚，未有能动者也。」
英文参考译文
Mencius said, 'When those occupying inferior situations do not obtain the confidence of the sovereign, they cannot succeed in governing the people. There is a way to obtain the confidence of the sovereign: if one is not trusted by his friends, he will not obtain the confidence of his sovereign. There is a way of being trusted by one's friends: if one do not serve his parents so as to make them pleased, he will not be trusted by his friends. There is a way to make one's parents pleased: if one, on turning his thoughts inwards, finds a want of sincerity, he will not give pleasure to his parents. There is a way to the attainment of sincerity in one's self: if a man do not understand what is good, he will not attain sincerity in himself. Therefore, sincerity is the way of Heaven. To think how to be sincere is the way of man. Never has there been one possessed of complete sincerity, who did not move others. Never has there been one who had not sincerity who was able to move others.'
重点修订页
人工补强的解释层
核心问题
为什么孟子把获于上、信于友、悦于亲，最后都追到‘诚身’？
直接回答
因为表面的信任、悦服、治理能力都不是孤立技巧。若一个人自身不诚，亲不会真悦，朋友不会真信，上位者也不会真获。孟子要把一切外在关系能力一路追回到内部有没有站真。
第一性原理
外部关系的稳定，最后取决于内部根基是否真实；没有诚，后面的大部分技巧都会逐层失效。
为什么重要
这章适合承接“思诚”“诚者天之道”“Mencius on sincerity”这类搜索，是修身与治人之间极关键的一段桥梁。
延伸阅读
这章在做什么
这章是《离娄上》第 12 / 28 章，最直接的进入线索是“居下位而不获于上，民不可得而治也”。放回全卷，它讨论的是自反、乱世与守道，并可与仁政互相印证。
更宽的搜索入口
如果你带着更宽的问题进入这一章，先从正确的 hub 页进入
全卷语境
《离娄上》经常从自反与守道的角度讨论乱世中的行动标准。
关联主题
引用提示
不要把‘诚’读成情绪真诚表达。孟子说的是人格与善的内在一致性，不明乎善，就谈不上真正诚身。