Mou Zongsan on Cheng Hao as a Proponent of ‘Mind as Principle’

Tsai Chia-he

Abstract： Zhu Xi derived his “great synthesis” of the philosophy of principle （lixue） from the two Cheng brothers， with Cheng Hao as the leader. However， New Confucian standard bearer Mou Zongsan classified Cheng Hao as representing the philosophy of “mind as principle” and his younger brother， Cheng Yi， as belonging to the lixue tradition. This article attempts to examine this opinion of Mous and establish the following three claims： （1） Cheng Hao derives from Daoist ideas of according with the nature of each thing and “taking the mind of the common people as the mind” and yet retains Confucian doctrines; （2） Cheng Hao did not teach that “mind is principle”; and （3） his philosophy of an objective principle was established on the idea of dealing with each thing according to its true nature and an immutable truth.

Keywords： driving cattle and riding horses， things rather than mind， Cheng Hao， lixue， mind as principle

Preface [Refer to page 34 for Chinese. Similarly hereinafter]

Traditionally the Cheng brothers， Cheng Hao 程顥 （1032–1085， a.k.a. Master Mingdao 明道） and Cheng Yi 程頤 （1033–1107， a.k.a. Master Yichuan 伊川）， were both classified as representatives of lixue 理學(xué) （the philosophy of principle）. Although Huang Zongxis 黃宗羲 （1610–1695） devoted separate entries to the two brothers in his magisterial Survey of Song and Yuan Confucians [宋元學(xué)案]， he never assigned them to separate schools of thought. Huang Baijia 黃百家 （1643–1709） presented them as unanimous in their portrayal of the Way and different merely in personality. Quan Zuwang 全祖望 （1705–1755） traced xinxue 心學(xué) （the philosophy of the mind） to Cheng Haos disciple Xie Liangzuo 謝良佐 （1050–1103）， but he did not trace it further back to Cheng Hao himself.

But Mou Zongsan 牟宗三 （1909–1995） believed that the two brothers were polar opposites in personality and this difference also caused their philosophies to diverge in character and orientation， with Cheng Hao representing a philosophy of “mind as principle” （心即理） and Cheng Yi as a spokesman of lixue proper. Cheng Yi understood li 理 （principle） as a being which is not active and extends down only as far as the nature （xing 性）， not all the way to the mind （xin 心）， wherefore the mind is not identical to principles and hence does not see the Way （dao 道）. In addition， Mou believed that， in the “Sayings of the Two Masters” [二先生語] comprising the first ten books of the Surviving Works of the Cheng Brothers of Henan [河南程氏遺書]， passages not explicitly attributed to one or the other of the two brothers mostly represented the words of Cheng Hao. And to Mou， it then appeared that Cheng Haos sayings emphasized synthesis and sudden awakening， whereas Cheng Yis thought seemed comparatively dull-minded and dualistic.

This author takes a different view from Mous. First， Cheng Yi self-identified as continuing Cheng Haos teaching， writing： “I have previously described [Cheng Haos] conduct， and my own Way is generally the same as his. In times to come， anyone wishing to know my [thinking] need only consults those documents and that will suffice.” Moreover， Cheng Yi did not evince to clear divergence from Cheng Hao such as claimed in Mous analysis.

Mou believed that even though Cheng Hao commented on the Great Learning， he did not regard it as important as his brother. Chengs commentary hails the Great Learning as the gateway text for developing virtue and cultivating oneself. Yet based on three passages from Cheng Haos commentary， Mou interpreted it as representing a different philosophical direction from Cheng Yis notion of “investigating things to fathom principles” （格物窮理）. Was Mou correct？

First， Cheng Hao is recorded as saying， “In the [Great Learnings] phrase， ‘Extending knowledge lies in investigating things， ‘investigating （ge 格） refers arriving. Some people interpret ‘investigating things to mean rectifying things， but this would be a case of two roots.” In glossing ge as “arriving” and opposing its interpretation as “rectifying things，” he was agreeing with Cheng Yi and Zhu Xi 朱熹 （1130–1200）.

In a separate passage， he is also reported to have said， “In the phrase， ‘Extending knowledge lies in investigating things， ‘investigating refers arriving. By exhausting principles one arrives at things， and thus the principles of things are completed.” Here too， he was agreeing with Cheng Yi and Zhu Xi. Relying on Huang Zongxis Survey of Song and Yuan Confucians Mou attributed this passage from the “Sayings of the Two Masters” to Cheng Yi， not Cheng Hao.

A third point concerns this passage： “Concerning the phrase， ‘Extending knowledge lies in investigating things， in coming to things， knowledge arises. Things submit to being things and do not enslave knowledge. Hence the sincerity of ones thoughts is not disturbed. Sincerity of thought being established， the mind is rectified. This is the beginning of learning.” Mou attributed this saying to Cheng Hao， dissenting in this case from Huang Zongxis Survey of Song and Yuan Confucians， and this ruling is entirely correct. The phrase “things submit to being things” refers to arriving at the principles of things and thus being able abide by the principles of external objects. Cheng Hao saw the Great Learning as the beginning to the enterprise of learning， just as Cheng Yi called it “the initial gateway for learning virtue” and Zhu Xi remarked that “one who studies must begin with this [text].” In this， the three men were of like mind.

In another passage， Cheng Hao is recorded is saying that， in the Book of Change， “‘three days before the beginning of events is a time to examine the reasons for events and to handle them， and ‘three days after is a time to examine what is to come and to prepare for it.” The distinction here between what is and the reason that it is so bears a certain correspondence Cheng Yi and Zhu Xis doctrine of ti yong 體用 （substance and function）. There are quite a few such examples， no signs of significant difference between Cheng Hao， Cheng Yi and Zhu Xi.

The present article， then， will examine three key points of Cheng Haos lixue.

Cheng Haos Philosophy as Refigured Daoism [36]

“The lixue tradition began with Zhou Dunyi 周敦頤 （1017–1073） and the Cheng brothers， who were mixed up in Daoism，” wrote Xiong Shili 熊十力 （1885–1968）， “and it took until the late Ming for Wang Fuzhi 王夫之 （1619–1692） to rise up and revive the tradition of lixue. Alas， its grandeur skipped over the worthies of the Song （960–1279）.” But Mou Zongsan， who was Xiongs student， took a different view from his teacher. Mou viewed Cheng Haos philosophy as one in which “mind is identical to principle，” a doctrine that he took for the orthodox Confucian view， and Cheng Yi and Zhu Xi as like a “second son who is nevertheless made patriarch of the clan.”

However， Xiongs remark was actually profoundly insightful. As Cheng Hao said in the “Letter on Calming Human Nature” [定性書]：

The constancy of Heaven and Earth is that their mind can pervade the myriad things and be no mind; the constancy of the sage is that his feeling abides by the myriad things and is no feeling. Thus there is no learning broader and more fair-minded， more naturally conforming to whatever comes than the learning of the superior person.

This view， in which the sages non-mind and non-feeling accords to the mind of the myriad things， is the same as Laozis when he says that “the sage has no invariable mind of his own; the sage makes the mind of the people his mind” and Zhuangzis when he says that “others cry so [the awakened person] cries too，” rather than dealing with others from the standpoint of his own nature. And Chengs “naturally conforming to whatever comes” is close to Zhuangzis saying that “the Consummate Person uses his mind like a mirror， rejecting nothing， welcoming nothing，” responding to each thing as it is and not exerting a force of its own.

Cheng Hao also spoke of “driving cattle and riding horses” rather than the opposite， since that would be absurd. Here the meaning is that one must respect the objectivity of the ways of things， abandon ones own fixations and abiding by things natures. This is similar to Zhuangzis story of the debate between the River God and Ruo of the Northern Sea：

The River God said， “What do you mean by the Heavenly and what by the Human？” Ruo of the Northern Sea said， “That cows and horses have four legs is the Heavenly. The bridle around the horsess head and the ring through the cows nose are the Human. Hence， it is said， “Do not use the Human to destroy the Heavenly， do not use the purposive to destroy the fated， do not sacrifice what you have attained [from Heaven] for the sake of mere names.” （Zhuangzi， chap. 17; Brook， 73）

From all of these instances we can see the Daoist influence of Laozi and Zhuangzi on Cheng Hao.

Cheng Haos Effort to Establish Objective Truth

in His Philosophy [37]

Cheng Hao attempted to establish an objective truth independent of the whims and wishes of humanity that does not， as Xunzi said， “survive because of the sage Yao or die because of the tyrant Jie” （Xunzi， “Discourse on Nature” [天論]）. Xunzis original meaning was of an objective， natural heaven. That is， Cheng Hao hoped to establish an objective Heavenly principle， not a principle that is identical to mind. As Mou defines “mind as identical to principle，” it is both extant and active， descending to the mind and subjectively and objectively replete. But in such a case， how could it be that principle does not descend to Yaos mind？ Below we will examine passages which will demonstrate Cheng Haos philosophy as objective lixue.

‘Dutifulness and Trustworthiness as Objective Heavenly Way and Ontological Principle [37]

Cheng Hao often said，

The sages often speak of dutifulness （zhong 忠） and trustworthiness （xin 信）， and the Way of Humanity lies merely in these. Without authenticity there would be no things and “its goings and comings have no fixed time and no one knows its home.” If there were no dutifulness and trustworthiness， could there then also be things？

Here Cheng Hao was borrowing Menciuss words to point out that the minds vagaries are not the same as the definite moral mind. Inasmuch as the human mind knows “no things without authenticity，” if it is authentic then this is dutifulness and trustworthiness. And in Cheng Haos definition， dutifulness and trustworthiness already rise to the level of objective Heavenly principle：

To regard oneself as the same as others is humaneness （ren 仁）. To put oneself in their position is reciprocity， which is quite close to the Way. Dutifulness and understanding are strung together on a single thread： dutifulness is the Way of Heaven and understanding is the Way of Humanity. To be dutifulness is to not be false; to be understanding is the means by which to practice dutifulness. With dutifulness as reality and understanding as its function is the great basis established and the Way achieved. This is something different from being not far from the Way， for the activity comes from Heaven.

Here “dutifulness” is defined as the Way of Heaven. With dutifulness being reality， “dutifulness and understanding” here is something undertaken by Heaven， wherefore it is without falseness. If it were something undertaken by humankind， there would be falseness. If Cheng Haos were really a philosophy of “mind as principle，” then this should be an act of both Heaven and humankind. But how then could it be that with Heaven there is no falseness and yet in humankind there is？ Hence we can see that Cheng Haos defining “dutifulness” as the Way and principle of Heaven is like his idea of an objective principle that “survive because of Yao or die because of Jie”： in his conception， dutifulness and trustworthiness is a real principle， just as in his “Essay on Understanding Humaneness” [識(shí)仁篇] he also portrays humaneness， rectitude， propriety， and discernment as actual principles， such that the human mind must act in accordance with dutifulness and trustworthiness.

Cheng Haos ‘Essay on Understanding Humaneness Does Not Teach Xinxue [37]

Concerning humaneness， Cheng Hao taught，

To learn， it is necessary first of all to understand humaneness， which is to be one body with all things. Rectitude， propriety， wisdom， and trustworthiness are all humaneness. Having understood this principle， one need only preserve it with sincerity and respect and need not regulate oneself vigilantly or cogitate exhaustively.

Cheng Haos “Essay on Understanding Humaneness” is one of his more famous writings and was the subject of a debate between Wang Yangmings disciple Ouyang De 歐陽德 （1496–1554） and Zhu Xi scholar Luo Qinshun 羅欽順 （1465–1547） over whether it should be considered a text of xinxue or lixue. Ouyang believed that because it frequently mentions mind and innate moral knowing and capacity （良知良能）， it should be classified as xinxue. However， Luo classified the text as lixue because it affirms that humaneness， rectitude， propriety， and discernment are principles. In Mou Zongsans view， even though Cheng Hao does discuss both mind and principle， he belongs in the “mind as principle” school of thought. We will now weigh this conclusion.

Referring to humaneness as being one body with all things， Cheng Hao says in his “Essay on Understanding Humaneness，” “The meaning of Zhang Zais 張載 （1020–1077） ‘Western Inscription [西銘] is a detailed discussion this reality （viz. that of humaneness） in detail. If we preserve this meaning， what else remains？” And in the Western Inscription we find not one word about mind. Hence it is wrong to view Cheng Hao as belonging to either the school of mind or the school of mind-as-principle.

Minds Impartial Accordance with Principle [38]

Elsewhere Cheng Hao taught， “To be without self is to approach people and matters from the perspective of those people and matters， not that of ones own self. A sage does not determine his conduct by his own self. Words are just opinions， whereas principle is seemingly not reducible to these words.” What he meant was that if one acts according to his or her own subjective lights， then there is no universality. Though xinxue talks of a universal innate moral knowing， people mostly obey not their innate moral knowing but their thoughts and feelings， and hence the sage does regulate his conduct by his own self.

The word “self” here has a negative connotation， as in Confuciuss “arbitrariness， inflexibility， rigidity， and selfishness.” On one hand， one ought not approach things and creatures in an anthropocentric way; on the other hand， if one does approach things subjectively， one cannot abide by their natures and take each thing as it is in itself and instead is full of selfish desire with which one then tries to dominate the world， resulting in jeopardy for the world. Instead one should recognize that an oxs nature is that it can plow and a horses is that it can be ridden and then follow their natures and employ them accordingly. By thus abiding their respective natures， one can achieve twice the results with half the effort and both oneself and other things will be at peace！

In his “Letter on Calming Human Nature，” Cheng Hao also exhorted people not to scheme for selfish purposes and manipulate and dominate the world. He said，

In every persons feelings there is some measure of vice that keeps them from conforming to the Way and there is great calamity to employing ones intelligence for selfish ends. When one is selfish， one cannot be obedient in ones efforts to things natures， and when one schemes， one cannot give spontaneous play to illumination.

The word “scheme” also bears a negative connotation， meaning not just “to exercise ones intelligence” but moreover to exercise a selfish and petty cunning rather than the great wisdom of one who abides by the Way.

Since it is easy for peoples minds and feelings to be subjective only， Cheng Hao taught people to embody the constancy of Heaven. Consider the passage quoted earlier：

The constancy of Heaven and Earth is that their mind can pervade the myriad things and be no mind; the constancy of the sage is that his feeling abides by the myriad things and is no feeling. Thus there is no learning broader and more fair-minded， more naturally conforming to whatever comes than the learning of the superior person.

Here， when Cheng Hao advocated pervading the myriad things with ones mind and yet being no mind and no feelings， he was proposing treating the mind like a mirror， as it were， namely according with things impartially and selflessly and not violating the principles of those things. What he described was a mind that accords with principle （心順理）， not a mind that is the principle.

Cheng Yi also Taught Mind， Nature， and Heaven as a Single Principle [38]

One passage in the “Sayings of the Two Masters” reads：

He often compared “using the mind to know Heaven” to living in the capital and only knowing that if you go out the western gate you can get to Changan. Here they are being spoken of as two places. But if you are fully authentic， being in the capital is being in Changan and there is no Changan to find outside of it. The mind is itself Heaven and plumb it completely is to know the nature and hence to know Heaven. On the spot one understands it and there remains nothing to seek elsewhere.

Mou Zongsan classified this as one of Cheng Haos sayings， based on Huang Zongxis Survey of Song and Yuan Confucians， writing that “this is also phrased particularly obviously in terms of sudden and perfect [awakening] and unity of mind， the nature， and Heaven. Here the basic reality of principle and the Way are definitely not ‘mere principle but a principle which is understood to be one with mind and spirit.”

Though this passage can indeed justly be described as drawing on the language of perfect and sudden awakening， we cannot then go on to criticize Cheng Yis concept of li as something that merely exists and does not act， because he too said that exhausting principle， completing the nature， and arriving at Heavens decree （ming 命） are all one. As he wrote， “Mencius said that ‘to plumb ones mind is to know ones nature and hence to know Heaven. Mind is the nature， which is Heaven—there is no difference among them.”

In Zhu Xis commentary on Mencius 7A：1， Zhu quoted “Master Cheng，” which should be taken as a reference to Cheng Yi， writing， “Master Cheng said that ‘mind is nature， which is Heaven， which is the one principle. Spoken of in terms of principle， it is called Heaven. Spoken of in terms of a persons endowment， it is called the nature. And with respect to its existing in all people， it is called mind.”

Should this be taken to mean that Cheng Yi taught the philosophy of “mind as principle”？ Both he and Zhu subscribed to the school of thought in which mind has a nature and that nature is principle， but they did not think that mind is the same thing as the nature and principle. In their view， it merely possesses them. These quotations from Cheng Yi merely emphasized the non-difference among the three in terms of their comprising a unified truth. But clearly there is insufficient evidence to classify Cheng Yi as a philosopher of “mind as principle.” By the same logic， there is also a problem with Mou Zongsans classifying Cheng Hao that way.

Which Brother Said This？ [39]

Mou Zongsan thought that in the “Sayings of the Two Masters，” sayings not specifically attributed to one or the other brothers mostly belonged to Cheng Hao. Sometimes he relied Huangs Survey of Song and Yuan Confucians， but in other cases he departed from Huang. As we can see， there exist many gray areas here where it is extremely hard to be certain.

Concerning the passage quoted above about “Changan outside the west gate，” even if Mou was right to attribute it to Cheng Hao， the passage says that “[Zhang Zai] often compared using the mind to know Heaven，” not that the mind is Heaven. The reason Mou viewed this passage as a monist statement belonging to the “mind is the principle” school of thought is that it plainly equates the mind with Heaven.

However， the passage is an explanation of Menciuss statement that “to plumb ones mind is to know ones nature and hence to know Heaven” and hence is speaking in line with Menciuss original. Cheng Haos words refer to using ones mind to know and accord with Heaven; they do not mean that ones mind is Heaven. Cheng Haos monism originates with the doctrine of the unity and basic oneness of heaven and humanity， which was common to all Song and Ming lixue. Not so the doctrine that mind is principle. Zhu Xi， for example， subscribed to the first doctrine but not the second; and Cheng Yi said that “the individuals mind is the mind of Heaven and Earth，” showing that Cheng Hao was not the only one who taught to unity of Heaven and Humanity.

Cheng Haos Emphasis on Objective and Independent Principle [40]

Cheng Hao said， “The [classical] phrase ‘King Wen ascends and descends on the left and the right of Di （the lord of heaven）， spontaneously and without thought following the norms of Di refers to according with the Heavenly principle without attempting any cleverness.” For individual subjectivity easily yields to partiality， whereas it is simpler and more straightforward just to accord with the objective principle of Heaven.

Cheng Haos “Letter on Calming Human Nature” says much the same thing. In response to a letter from Zhang Zai asking whether nature must not by influenced by external objects， Cheng Hao answered that it is better to forget the distinction between internal and external and not spurn external things：

All peoples feelings are obscured in some way， such that they cannot follow the Way. In general the trouble lies in selfishness and resorting to the exercise of cunning. Being selfish， one cannot take purposive action to respond to things， and being cunning， one cannot be at home with enlightenment. For a mind that hates external things to seek illumination in a mind where nothing exists， is to look for a reflection on the back of a mirror. . . . Instead of looking on the internal as right and the external as wrong， it is better to forget the distinction. When such a distinction is forgotten， the state of quietness and peace is attained. Peace leads to calmness and calmness leads to enlightenment. When one is enlightened， how can the response to things become an impediment？ The sage is joyous because according to the nature of things before him， he should be joyous， and he is angry because according to the nature of things before him he should be angry. Thus the joy and anger of the sage do not depend on his own mind but on things.

Here we can see that Cheng Hao looked to an objective Heavenly principle and standard and advocated acting according to principle and impartially and thereby dispensing with selfishness.

Cheng Hao Was Not a Philosopher of ‘Mind as Principle [41]

By identifying Cheng Hao with the doctrine that “mind is principle，” Mou Zongsan meant that Heavenly principle possesses vitality and can act and also descend into mind. He thought Cheng Hao was succeeded by Hu Hong 胡宏 （1106–1162）， who represented the apogee of Song–Ming Neo-Confucianism and whose influence could be found in Lu Xiangshan 陸象山 （1139–1193） and Wang Yangming 王陽明 （1472–1528）. But in keeping with the arguments above， this author believes that Cheng Hao built his philosophy on the idea of an objective principle， not a doctrine that “mind is principle”：

The two Chengs explained “the investigation of principle to the utmost and the full development of nature to fulfill destiny” by saying， “merely to investigate principle to the utmost is to fulfill destiny.” Zhang Zai said， “Here it would be a mistake to go too quickly， for in any case there is a proper order here. One first needs to investigate principle to the utmost and then can fully develop ones own nature and， by extension， fully develop human nature. Since fully developing human nature requires that one do so together with the myriad things， only after doing so does one fulfill the Heavenly Way.”

Mou Zongsan quoted this in his chapter on “Cheng Haos Monism” [一本論]， where he interpreted the phrase “the two Chengs” to mean only Cheng Hao， but this attribution is not necessarily correct. The passage is taken from the Surviving Works of the Cheng Brothers of Henan， compiled by Su Bing 蘇昞 （fl. 1076） under the title “The Debate in Luoyang” [洛陽議論]. Su would have attributed the words to “Mingdao” if they had been spoken by Cheng Hao or to “Yichuan” if by Cheng Yi， but the fact that he attributed them to “the two Chengs” means that they were assented to by both brothers and cannot be assigned to Cheng Hao alone.

As is recorded in the Collected Works of the Two Chengs [二程集]， “In 1077， Zhang Zai was passing through Luoyang and debated the two masters. This occurred earliest among the sayings and because they were intermingled with Zhangs contentions， those are included here.” It is clearly stated here that Zhang came to debate the two Cheng brothers， so if Cheng Hao had said something with which Cheng Yi did not agree， there ought to have been some further statement recorded. Since there is no dissenting statement from Cheng Yi， the line represents their shared position and cannot be taken as representing only Cheng Haos thinking.

Elsewhere in Mous chapter on Cheng Hao， Mou quoted a saying of his which reads as follows：

Han Wei 韓維 （1017–1098） asked Cheng Hao， “If there were someone who were completely illumined at once， would you believe it？” Cheng answered， “If there really were such a person， how could I not believe？ There must surely be people who are born with such understanding， but I have not seen one. All learners are called such [because they learn]. Mencius says， “To fully develop the mind is to know ones nature， which is to know heaven. To preserve ones mind and nourish ones nature is the way to serve heaven.” These words stand supreme.

Mou saw this passage as an expression of Cheng Haos alleged monist belief that heaven humanity are one whole and one reality， not two distinct principles. However， Mou punctuated the passage differently from the Beijing Zhonghua Book Company edition of 1981 （which we have used above） and instead took the passage to say “All learners are such. Mencius made a point of saying.” Mous reading is manifestly less appropriate to the text.

This is because the character “but” marks a concessive relationship and actually makes the point that people who know （their nature and heaven） should be very rarely and seldom encountered. Hence learners should begin with “knowing through learning，” and it is in virtue of this that they are learners， not because of some innate knowing. Cheng Hao repeatedly emphasized that a learners cultivation is not the cultivation of a sage， the former referring to learning the mundane so as to arrive at the lofty. But Mou Zongsan maintained that Cheng Hao taught the sudden enlightenment doctrine that mind is precisely principle and taught that exclusively. Reading the passage in Mous way （“All learners are such”） amounts to say that learners are born knowing （the nature and heaven）. On this reading， the whole passage then seems to be talking about the innately illumined people who have “never been seen” and focusing on their sudden and perfect illumination rather than the process of mundane learning in hopes of arriving at the lofty. Cheng Hao frequently accused people such as this， who “only wanted to reach upward toward the lofty but not bother with learning mundane things” as lapsing into a Chan Buddhist attitude. Are we to believe that he himself then went down the Chan path？！

Elsewhere he is recorded as saying：

How can Buddhists， with their terror of birth and death and their selfishness， be called impartial？ They attend only to reaching toward the lofty but have no mundane learning， so what loftiness do they achieve？ If the two are disconnected and not mutually implicating， then this is not the way. As Mencius says， “To fulfill ones mind is to know ones nature.” This is what they call “knowing mind and seeing nature.” If they would just “preserve their mind and nourish their nature，” they would have no trouble.

Here Cheng Hao was criticizing Buddhists for searching only for the lofty and not learning the mundane， talking only of sudden enlightenment and “the immediate this” （當(dāng)下）， and having no concept of cultivation by preserving the mind and nourishing the nature. Thus we can see that， in Cheng Haos opinion， we need mundane learning as well and not just sudden enlightenment. Moreover， we see Cheng Hao criticizing Buddhists for their selfishness， and owing to his emphasis on impartiality， magnanimity， attending to things as they are in themselves， and acting according to the principle， he should be classified within the philosophy of lixue and not that of “mind as principle.” “Learning humaneness through equitability” is not the sole property of Cheng Yi; after all， Cheng Hao taught it first.

Conclusions and Reflections [43]

Mou Zongsan assigned the Cheng brothers to two separate philosophical systems， with Cheng Yi being succeeded by Zhu Xi and Cheng Hao being succeeded by Hu Hong and， through Hu， connected to Lu Xiangshan and Wang Yangming. But the two brothers were only a year apart in age and very close to one another， and Cheng Yi presented himself as his brothers successor. Could he seriously not have understood his brothers teaching and wandered off down a whole different path？ This strains credibility.

Though the two brothers were not entirely alike， in their basic orientations they both properly belong to the lixue tradition. Cheng Yi did go a step further， mostly on the topic of self-cultivation， but there was no difference such as Mou alleges of “mind as principle” on one and “mere existence but no activity” on the other. The two Cheng brothers do not represent different philosophical schools， just earlier and later developments in the same system.

As Tang Junyi 唐君毅 （1909–1978） wrote， “Cheng Yis thought really was essentially a further development of Cheng Haos. . . . His difference [from Cheng Hao] was not fundamental， instead representing just a further continuation， and existed simply because Cheng Yi advanced his brothers study of methods of self-cultivation further.” If Mou Zongsan were right about the Cheng brothers， they would have been as opposed as Zhu Xi and Lu Xiangshan and probably would have clashed early on. This author wishes to return to the view of Huang Baijia and Tang Junyi that the brothers represented a common philosophical lineage and merely differed in their approach to the subject of cultivation differently， their development， and their accomplishments in self-cultivation， nonetheless both belonging for the most part to the tradition of Cheng–Zhu lixue rather than separate and opposed schools of thought.

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Translated by Jason T. Clower