丹溪曰∶按《内经》以下，皆谓外中风邪，然地有南北之殊，不可一途而论。惟刘河间
作将息失宜，水不制火者极是。由今言之，西北二方，亦有真为风所中者，但极少耳；东南
之人，多是湿土生痰，痰生热，热生风耳。
据丹溪引《内经》以下皆谓外中风邪之说，不知《内经》之凡言风者，皆以外感为言，
原非后世之所谓中风也。观《难经》五种伤寒之意可知矣。而丹溪之言，岂得内经之本意乎
？至若东南之人，只是湿痰生热，热生风，此仍述河间热甚之说，而非风等证。岂皆热病？即
云为痰，又岂无寒痰。而何以痰即生热，热即生风也？且非风则已，是风则南北俱有，若云
东南寒少，未必杀人则可，而云风少则不可也。非痰则已，是痰亦南北俱有。若水土之外湿
，东南虽多；而乳酪之内湿，则西北尤多也。虽痰之为物，本为湿动。然脾健则无，脾弱则
有，而脾败则甚。是可见因病所以生痰，非因痰所以生病也。凡治失其本而欲望病愈者，未
之有也。
又丹溪曰∶半身不遂，大率多痰。在左属死血与瘀血，宜四物汤加桃仁、红花、竹沥、
姜汁；在右属痰属气虚，宜二陈汤、四君子汤加竹沥、姜汁。
据丹溪此说，若乎近理，故人多信之，而不知其有不然也。夫人身血气，本不相离，焉
得以左为血病，右为痰气耶？盖丹溪之意，以为肝属木而位左，肝主血也；肺属金而位右，
肺主气也；脾属土而寄位西南，故亦在右，而脾主湿与痰也。然此以五行方位之序，言其理
耳。岂曰西无木，东无金乎？且各经皆有左右，五脏皆有血气。即如胃之大络，乃出于左乳
之下，则脾胃之气亦出于左。又岂左非脾，右非肝，左必血病，右必痰气乎？然则何以辨之？
此惟《内经》以阴阳分血气，以左右言轻重，则至当也。经曰∶左右者，阴阳之道路也。又
曰∶阴胜则阳病，阳胜则阴病。又曰∶女子右为逆，左为从；男子左为逆，右为从。夫阳病
者，即气病也。气本乎阳，而阴邪胜之则病也。阴病者，即血病也，血本乎阴，而阳邪胜之
则病也。从者病轻，男病宜右，女病宜左也。逆者病重，男病畏左，女病畏右也。以此辨之
，而再参以脉色，察其病因，则在气在血，或重或轻，斯得其真矣。若谓左必血病，右必痰
气，则未免非痰治痰，非血治血，而诛伐无过，鲜不误矣。
朱丹溪说：按照《内经》以下的论述，都认为这是外感中风邪气所致，然而地理上有南北的差异，不能一概而论。只有刘河间提出的因调养失当、肾水不能制约心火导致病情加重，是非常正确的。从当今的情况来看，西北两个地区，也有真正被风邪中伤的情况，但极少；东南地区的人，多是湿土生痰，痰产生热，热产生风罢了。
根据丹溪引用《内经》以下认为都是外感中风邪气的说法，他不知道《内经》中凡是提到“风”的，都是指外感病，原本就不是后世所说的“中风”。看《难经》中关于五种伤寒的意思就可以知道了。而丹溪的话，难道符合《内经》的本意吗？至于东南地区的人，只是湿痰生热，热生风，这仍然是阐述河间“热甚”的说法，而不是“非风”等证候。难道都是热病吗？即使说是因为痰，又难道没有寒痰吗？为什么痰就产生热，热就产生风呢？况且如果不是“非风”则罢，如果是“风”，那么南北都有；如果说东南寒冷少，未必致死是可以的，但说风邪少就不对了。如果不是痰则罢，如果是痰，也是南北都有。如果水土之外湿，东南虽然多；但乳酪之内湿，西北尤其多。虽然痰这种物质，本来是由湿引起的。但是脾健运就没有痰，脾虚弱就有痰，脾败坏则痰更严重。由此可见，是因为生病所以生痰，不是因为生痰所以生病。凡是治疗失去了根本而希望病愈的，从来没有过。
另外丹溪说：半身不遂，大率多是由于痰。在身体左侧属于死血和瘀血，适宜用四物汤加桃仁、红花、竹沥、姜汁；在身体右侧属于痰和气虚，适宜用二陈汤、四君子汤加竹沥、姜汁。
根据丹溪的这个说法，似乎接近道理，所以很多人相信它，却不知道其中有不正确的地方。人的身体气血，本来是不分离的，怎么能把左边当作血病，右边当作痰气病呢？大概丹溪的意思是，认为肝属木而位居左，肝主血；肺属金而位居右，肺主气；脾属土而寄居在西南位，所以也在右边，而脾主湿与痰。然而这是用五行方位的顺序来谈论其理论罢了。难道说西边没有木，东边没有金吗？况且各条经络都有左右，五脏都有血气。就像胃的大络，是从左乳下发出的，那么脾胃之气也从左边发出。又怎么是左边不是脾，右边不是肝，左边一定是血病，右边一定是痰气病呢？那么如何辨别呢？这只有《内经》用阴阳来区分血气，用左右来说明病情的轻重，才是最为恰当的。经文说：左右，是阴阳运行的道路。又说：阴胜则阳病，阳胜则阴病。又说：女子右边为逆，左边为顺；男子左边为逆，右边为顺。所谓阳病，就是气病。气本乎阳，而阴邪胜过它则生病。所谓阴病，就是血病，血本乎阴，而阳邪胜过它则生病。顺者病轻，男病宜见于右，女病宜见于左。逆者病重，男病畏惧见于左，女病畏惧见于右。用这个来辨别，再参考脉象和面色，考察病因，是在气还是在血，或者病重或病轻，这样就能得到真相了。如果说左边一定是血病，右边一定是痰气病，那就未免不是治痰只治痰，不是治血只治血，从而诛伐无过错之处，很少有不犯错误的。
Zhu Danxi stated: According to the discussions following the *Neijing* (Inner Canon), it is generally believed that this condition results from external wind-pathogen invasion. However, due to geographical differences between the north and south, one cannot apply a single standard universally. Only Liu Hejian’s assertion that improper lifestyle management leading to kidney water failing to control heart fire is extremely correct. Speaking from the present perspective, in the two regions of the northwest, there are indeed cases of true wind-stroke, but they are rare; whereas in the southeast, people mostly suffer from damp-earth generating phlegm, phlegm generating heat, and heat generating wind.
Regarding Danxi’s citation of the *Neijing* and subsequent texts claiming all such conditions are caused by external wind-pathogen invasion, he was unaware that whenever the *Neijing* mentions "wind," it refers to external contraction, which originally did not mean what later generations called "Zhong Feng" (Wind Stroke). This can be understood by observing the concept of five types of Shanghan (Cold Damage) in the *Nanjing* (Classic of Difficult Issues). Does Danxi’s statement align with the original intent of the *Neijing*? As for people in the southeast, their condition stems merely from damp-phlegm generating heat, and heat generating wind. This merely reiterates Hejian’s theory of excessive heat, rather than referring to conditions like "Fei Feng" (Non-Wind). Are all these heat diseases? Even if attributed to phlegm, how can we assume there is no cold-phlegm? Why must phlegm generate heat, and heat generate wind? Furthermore, if it is not "Fei Feng," then fine; but if it is wind, it exists in both north and south. It may be true that the scarcity of cold in the southeast makes it less likely to be fatal, but claiming that wind pathogens are scarce there is incorrect. If it is not phlegm, then fine; but if it is phlegm, it also exists in both north and south. While external dampness from soil and water is more common in the southeast, internal dampness from dairy products is particularly prevalent in the northwest. Although phlegm is fundamentally activated by dampness, its presence depends on the spleen: when the Spleen Qi is robust, there is no phlegm; when weak, phlegm appears; when failing, phlegm becomes severe. Thus, it is evident that illness generates phlegm, not that phlegm generates illness. There has never been a case where treatment misses the root cause yet expects recovery.
Furthermore, Danxi stated: Hemiplegia is largely due to phlegm. Lesions on the left side belong to dead blood and stasis, treated with Siwu Tang (Four Substance Decoction) added with Tao Ren (Peach Kernel), Hong Hua (Safflower), Zhuli (Bamboo Sap), and Jiangzhi (Ginger Juice); lesions on the right side belong to phlegm and Qi deficiency, treated with Erchen Tang (Two-Aged Decoction) or Sijunzi Tang (Four Gentlemen Decoction) added with Zhuli and Jiangzhi.
This statement by Danxi seems plausible, hence widely accepted, yet it contains inaccuracies. In the human body, Blood and Qi are inseparable; how can the left be exclusively associated with Blood disease and the right with Phlegm-Qi disease? Danxi’s reasoning appears to be based on the Liver belonging to Wood and residing on the left, governing Blood; the Lung belonging to Metal and residing on the right, governing Qi; and the Spleen belonging to Earth, residing in the southwest, thus also on the right, governing Dampness and Phlegm. However, this is merely applying the theoretical sequence of Five Elements and directions. Does this imply there is no Wood in the west or no Metal in the east? Moreover, every meridian has left and right aspects, and every Zang organ possesses both Blood and Qi. For instance, the great collateral of the Stomach emerges below the left breast, indicating that Spleen and Stomach Qi also emanate from the left. How can one claim the left is not Spleen, the right is not Liver, the left must be Blood disease, and the right must be Phlegm-Qi disease? Then how should differentiation be performed? Only the *Neijing*’s method of distinguishing Blood and Qi via Yin and Yang, and assessing severity via left and right, is most appropriate. The Classic states: "Left and right are the pathways of Yin and Yang." It also says: "Excess Yin causes Yang pathology; excess Yang causes Yin pathology." Additionally: "In women, the right is Ni (Rebellious/Severe), the left is Shun (Smooth/Mild); in men, the left is Ni, the right is Shun." Yang pathology refers to Qi disease; Qi belongs to Yang, and when Yin pathogens overcome it, disease occurs. Yin pathology refers to Blood disease; Blood belongs to Yin, and when Yang pathogens overcome it, disease occurs. Shun indicates mild disease; for men, manifestation on the right is favorable; for women, manifestation on the left is favorable. Ni indicates severe disease; for men, manifestation on the left is feared; for women, manifestation on the right is feared. By using this method for differentiation, combined with pulse and complexion analysis to investigate etiology, one can determine whether the issue lies in Qi or Blood, and whether the severity is high or low, thereby arriving at the truth. To assert that the left must be Blood disease and the right must be Phlegm-Qi disease would inevitably lead to treating phlegm only as phlegm and blood only as blood, punishing areas without fault, and rarely avoiding error.