不同于孔子对气的简略提及，孟子将“气”正式引入儒学范畴，孟子之“养气说”也为后世儒家功夫论的构筑提供依据。相较于揭示人皆具有向善之禀赋的心性论，孟子气论旨在证明：人可通过长期的道德存养，实现自身向善禀赋和为善能力的双重确证。这一确证过程被孟子以“不动心”简述之，包括知言与养气两个方面。知言的涵义是，全面地掌握言语、学说和思想的本质，不为外界之“言”所遮蔽。养气是“养浩然之气”的简称。孟子未使用“养”字搭配与志协调相随的气。夜气的固定搭配则为“存”。唯有浩然之气，孟子称之为“养”。而“我善养吾浩然之气”是孟子对自身道德境界和的充分肯定，亦表明浩然之气内在于人，用“道”“义”悉心养护实现浩然之气体量的无限推扩和道德境界的持续提升，最终与天地融通为一。对于知言和养气的关联，宋儒多赞成将知言置于养气之前，由知言方能推出养气。明末儒者黄宗羲则认为先后本末的区分不适用于表述知言与养气的关系。这一分歧表明如何界定二者关联的问题由来已久，近现代学者多认为知言与养气是儒家功夫论中两个并列且指向不同的分域。其实，孟子视知言、养气为价值相当、不分主次的功夫。二者均为达至不动心境界的方法。读《知言养气章》愈久，愈感到此章义理之艰深。究其原因，是此章有较多难于理解的概念和问题。例如：如何理解孟子的“不动心”、如何理解“不得于言，勿求于心；不得于心，勿求于气。”这一疑难句式、如何理解“持志”与“无暴其气”的关联、知言的涵义谓何……厘清这些问题方能接近《知言养气章》之旨。简言之，孟子的“不动心”是讲“心”不为负面因素牵引，在任何情形均能明辨是非、镇定自若。“不得于言……勿求于气”一句揭示孟、告对于言与心、心与气看法的分歧。孟子之“我知言”正是对告子“不得于言”至于以义为外的驳斥。其后“持其志，无暴其气……是气也，而反动其心。”一句旨在论证个体的“意志”对于“充体之气”具有统摄作用，同时“充体之气”对个体意志也具有反作用。《知言养气章》的核心是揭示浩然之气的固有特征。孟子未详说其形成根据与过程，但浩然之气作为内在于人的道德实存，须以人之性善、才善禀赋作为先天发生机制。“集义”是浩然之气养成的根本方法。集义的内涵亦证明道义生于内而非自外，而勿正心，勿忘、勿助长则是养气具体条目，可涵泳守护浩然之气。本文亦探究“不动心”“知言”和“存夜气”各自与“养浩然之气”的关联，文章结语部分对孟子气论的意义展开评价，揭示养浩然之气对古代中国士大夫勇毅果决之气魄的塑造及当今时代价值。

The longer I read the Chapter on Understanding Words and Nourishing QI. The more I feel that the chapter is difficult and profound. The reason is that there are many difficult concepts and problems in this chapter. For example: how to understand Mencius not to be moved, how to understand do not speak, do not seek from the heart. Not from the heart, not from the spirit. This difficult sentence pattern, how to understand the relationship between holding ambition and no violent QI, what is the meaning of knowledge only by clarifying these questions can we approach the purpose of the Chapter on Understanding Words and Nourishing QI. In short, Mencius's unmoving heart means that the heart is not drawn by negative factors, and can distinguish right from wrong and be calm in any situation. It must not be said the sentence Do not seek QI reveals the differences between the views of Mencius and GAO ZI on speech and heart, heart and QI. Mencius I know word is just a refutation of his accusation that words must not be spoken and that righteousness should be taken as an exception. Then hold its ambition, no violence its gas is the QI that moves the heart. One sentence aims to demonstrate that the will of the individual has a controlling effect on the QI of the full body and the QI of the full body also has a counter effect on the individual will. The core of the Chapter is to reveal the inherent characteristics of noble spirit. Mencius did not elaborate on the basis and process of its formation, but the noble spirit, as a moral existence inherent in human beings, must take the good nature of human beings and the good endowment as an innate mechanism. Collection of meaning is the fundamental way to develop noble spirit. The connotation of the collection of meaning also proves that morality is born inside rather than outside, and do not correct the heart, do not forget, do not encourage is a specific item of nourishing QI, can be connotative to protect the noble spirit. This paper also explores the relationship between not moving heart, knowledge of word and preserving night QI respectively and raising noble spirit. The conclusion of this paper evaluates the significance of Mencius theory of QI, and reveals the shaping of raising noble spirit for the courage and determination of ancient Chinese literati and its value in the current era.