东垣《发明》曰∶阳之气，以天地之疾风名之。此中风者，非外来风邪，乃本气自病也
。凡人年逾四旬，气衰之际，或忧喜忿怒伤其气者，多有此疾，壮岁之时无有也；若肥甚者
则间有之，亦是形盛气衰而如此耳。治法当和脏腑，通经络，便是治风也。
据东垣年逾四旬气衰之说，其发明病机，切中病情，诚出诸贤之表者，余深服之。然忧
、喜、忿、怒伤气者固有此疾，而酒色劳倦伤阴者尤多此疾。何以言之？盖气生于阳，形成
于阴。余尝曰∶察阳者，察其衰与不衰。察阴者察其坏与不坏。夫阳衰则气去，故神志昏乱
；阴亏则形坏，故肢体废弛，此衰坏之谓也。所以此病多在四旬之外，正以其渐伤渐败，而
至此始见其非外感，而总由内伤可知也。今以气脱形坏之病，顾可谓之风热而散之攻之也否
乎？
又东垣曰∶中血脉则口眼歪，中腑则肢节废，中脏则性命危，三治各不同。中血脉者，
外有六经之形证，则从小续命汤加减。中腑者内有便溺之阻格，宜三化汤等通利之。外无六
经之形证，内无便溺之阻隔，宜养血通气。大秦艽汤、羌活愈风汤主之。
据东垣、河间之说，若有同者，若有异者。如云中腑中脏，本皆同也。而东垣又云中血
脉，则稍异矣。又如续命汤，在河间则以治腑病，东垣则以治血脉；三化汤在河间用以治中
脏，而东垣用以治中腑，则又异矣。此或因证施治，各有所宜，姑无论也。再如河间曰∶此
非肝木之风，亦非外中于风。东垣亦曰∶非外来风邪，乃本气自病也。夫皆曰非风，而又皆
曰中腑中脏，不知所中者为何物，则分明又指为风矣。夫既曰将息失宜，又曰气衰所致，本
皆言其虚也。而治法皆用汗下，则分明又作实邪矣。此等名目混乱，泾渭不分，若曰是，若
曰非，而含糊于可否之间，因致后学茫然莫知所宗。正以议论日多，不得其要，反滋千古疑
窦，深可慨也。至若续命、三化等汤，恐亦非神衰形坏之人所能堪者。故凡读书稽古之士，
宜加精究。勿谓古人之法如此，便可执而混用。
李东垣在《脾胃论·发明》中说：人体的阳气，可以用天地间迅猛的风来命名。这种“中风”病，并非由外界侵入的风邪引起，而是人体自身元气病变所致。凡是年龄超过四十岁、处于元气衰退阶段的人，或者因忧愁、喜悦、愤怒等情绪损伤了元气的人，很容易患这种疾病；而在壮年时期通常不会得此病；如果是特别肥胖的人，偶尔也会患病，这也是因为形体虽盛但元气衰败的缘故。治疗原则应当调和脏腑功能，疏通经络，这就是治疗风病的方法。
根据李东垣关于“年过四十则气衰”的说法，他对发病机理的阐述切中病情要害，确实超出了其他医家的水平，我对此深表信服。然而，因忧、喜、怒、恐等情志伤气的固然有此病，但因酒色过度、劳累疲倦而损伤阴精的人，患此病的更多。为什么这么说呢？因为气生于阳，形体成于阴。我曾经说过：观察阳气，是看它的衰弱与否；观察阴精，是看它的亏损与否。阳气衰弱则元气耗散，所以神志昏乱；阴精亏虚则形体败坏，所以肢体废弛不用，这就是所谓的“衰”和“坏”。因此，这种病多在四十岁以后出现，正是因为身体逐渐受损、逐渐败坏，到了这个时候才显现出来，由此可知这并非外感病，而完全是内伤病。如今面对这种气脱形坏的疾病，怎么能说是风热之邪而用发散攻伐的方法治疗呢？
另外，李东垣说：邪中血脉，则口眼歪斜；邪中腑，则四肢关节废用；邪中脏，则性命垂危，这三种情况的治疗方法各不相同。中血脉者，外部有六经的症状表现，应使用小续命汤加减治疗。中腑者，内部有大便小便阻滞不通的情况，宜用三化汤等药物通利二便。如果外部没有六经的症状表现，内部也没有二便的阻隔，宜采用养血通气的方法，以大秦艽汤或羌活愈风汤为主治方剂。
根据李东垣和刘河间的学说，他们的观点既有相同之处，也有不同之处。例如谈到中腑、中脏，原本意思是一样的。但李东垣又提到中血脉，这就稍有不同了。又如续命汤，刘河间用来治疗腑病，而李东垣用来治疗血脉病；三化汤在刘河间那里用于治疗中脏，而李东垣用来治疗中腑，这又是不同的。这些差异或许是因为辨证施治，各有适宜之处，暂且不论。再如刘河间说：这不是肝木之风，也不是外来的风邪。李东垣也说：不是外来风邪，而是本气自病。两人都说不是风，却又都提到中腑、中脏，不知道所中的到底是什么东西，这分明又是指向风邪了。既然都说调养失当、气衰所致，本来都是在说虚证。但治疗方法却都用发汗和泻下法，这分明又把病当作实证邪气了。这些名目混乱，界限不清，似是而非，含糊其辞，导致后学者茫然不知遵循什么准则。正因为议论越来越多，却抓不住要领，反而滋生了千古疑窦，实在令人感慨。至于像续命汤、三化汤这类方剂，恐怕也不是元气衰微、形体败坏的人所能承受的药力。所以，凡是读书考据的古籍研究者，应该加以精细研究。不要认为古人的方法就是这样，就可以机械地照搬混用。
Li Dongyuan stated in his work *Fa Ming* (Invention of Principles): "The Yang Qi of the human body can be named after the swift wind of heaven and earth." This condition known as Zhong Feng (Wind Stroke) is not caused by exogenous Wind Evil invading from outside, but is a disease originating from the internal dysfunction of one's own Yuan Qi. Generally, individuals over forty years of age, who are at a stage of declining Qi, or those whose Qi has been damaged by emotions such as worry, joy, anger, or fear, are prone to this disease; it is rarely seen during their vigorous youth. Even among those who are extremely obese, it may occasionally occur, which is also due to the condition where the physical form is robust but the Qi is deficient. The treatment principle should focus on harmonizing the Zang-Fu organs and unblocking the meridians; this constitutes the treatment for Wind diseases.
Regarding Li Dongyuan's assertion that "Qi declines after forty," his elucidation of the pathogenesis hits the mark of the clinical presentation, truly surpassing other physicians. I deeply admire this view. However, while those whose Qi is damaged by emotions like worry, joy, and anger do suffer from this disease, there are even more cases resulting from Yin injury caused by excessive alcohol and sexual indulgence, as well as fatigue and exhaustion. Why is this so? Because Qi originates from Yang, while the physical form is formed by Yin. I have previously stated: "When observing Yang, observe whether it is declining or not; when observing Yin, observe whether it is damaged or not." When Yang declines, Qi dissipates, leading to confusion of spirit and consciousness; when Yin is deficient, the physical form deteriorates, leading to flaccidity and paralysis of the limbs. This is what is meant by 'decline' and 'deterioration.' Therefore, this disease mostly appears after the age of forty, precisely because the body gradually suffers damage and deterioration, manifesting only at this stage. It becomes clear that this is not an external contraction but entirely an internal injury. Given a disease characterized by Qi collapse and physical deterioration, how can it be treated as Wind-Heat and subjected to dispersing and attacking methods?
Furthermore, Li Dongyuan stated: "If the Wind strikes the blood vessels, there will be deviation of the mouth and eyes; if it strikes the Fu organs, the limbs and joints become useless; if it strikes the Zang organs, life is endangered. The treatments for these three conditions differ." For cases striking the blood vessels, where there are exterior manifestations corresponding to the Six Channels, Xiao Xuming Tang (Minor Continuation Life Decoction) should be modified and used. For cases striking the Fu organs, where there is internal obstruction of urination and defecation, Sanhua Tang (Three Transformations Decoction) or similar formulas should be used to promote free flow. If there are no exterior manifestations of the Six Channels and no internal obstruction of urination and defecation, nourishing Blood and promoting Qi circulation is appropriate, primarily using Da Qin Jiao Tang (Great Gentian Root Decoction) or Qiang Huo Yu Feng Tang (Notopterygium Decoction for Dispelling Wind).
Comparing the theories of Li Dongyuan and Liu Hejian, there are both similarities and differences. For instance, regarding Zhong Fu (Stroke of Fu Organs) and Zhong Zang (Stroke of Zang Organs), the original meaning was the same. However, Li Dongyuan added the concept of Zhong Xue Mai (Stroke of Blood Vessels), which introduces a slight difference. Similarly, Xuming Tang was used by Liu Hejian to treat Fu organ diseases, whereas Li Dongyuan used it for blood vessel strokes; Sanhua Tang was used by Liu Hejian for Zhong Zang, while Li Dongyuan applied it to Zhong Fu. These discrepancies might arise from syndrome differentiation and specific indications, which we may set aside for now. Additionally, Liu Hejian stated: "This is not the Wind of Liver Wood, nor is it Wind invading from outside." Li Dongyuan also said: "It is not exogenous Wind Evil, but a disease of the native Qi." Both deny it is Wind, yet both refer to Zhong Fu and Zhong Zang, leaving unclear what exactly is being struck, which clearly points back to Wind. Since both attribute the cause to improper lifestyle and Qi deficiency, they essentially describe a Deficiency pattern. Yet, their treatments employ sweating and purging methods, effectively treating it as an Excess pathogen. Such terminological confusion and lack of distinction between clear boundaries create ambiguity, causing later students to be bewildered about which school to follow. As discussions multiply without grasping the essence, they instead generate eternal doubts, which is deeply regrettable. Formulas such as Xuming Tang and Sanhua Tang are likely too harsh for patients with depleted Qi and deteriorated forms. Therefore, scholars who study ancient texts should conduct rigorous investigations. One should not assume that because ancient methods were recorded this way, they can be mechanically applied indiscriminately.