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Cangzhu (Atractylodis Rhizoma), with a pungent odor and strong flavor, has a dispersing nature capable of inducing sweating. It enters the Foot-Yangming Stomach Meridian and the Foot-Taiyin Spleen Meridian. It can also eliminate dampness, remove cold qi from the chest, ward off mountainous miasma, resolve the qi of plagues and corpse ghosts, and is particularly effective in stopping heart pain. However, its dispersing action exceeds its tonifying action, so it cannot be compared with Baizhu (Atractylodis Macrocephalae Rhizoma). The *Shennong Bencao Jing* states: "If one desires longevity, one should consume Shanjing." This refers to Baizhu, not Cangzhu. Cangzhu can ward off evil pathogens but cannot be used to tonify healthy qi. Various materia medica texts confuse the two, which is erroneous. Nevertheless, when Cangzhu is used skillfully, its efficacy is as immediate as an echo. For instance, heart pain arises when dampness夹杂着 cold pathogens invades the upper burner affecting the Danzhong region; although Cangzhu cannot directly enter the Danzhong, it excels at traversing the Large Intestine to dispel dampness, which is its specific merit. Therefore, when used together with Chuanwu (Aconiti Radix Lateralis Preparata), it guides the damp pathogen downward, preventing cold qi from invading the Danzhong, thereby immediately alleviating heart pain. If Baizhu were used instead of Cangzhu, it would guide the pathogen into the Heart, causing great harm.

One might ask: Cangzhu is a Yang herb, most capable of warding off evil pathogens; logically, it should clear all pathogens. Why does it sometimes fail? Wherever pathogens gather, the body's qi must be deficient. However, qi deficiency varies: there is qi deficiency accompanied by damp-phlegm, and qi deficiency accompanied by dry-phlegm. Cangzhu tonifies qi and excels at dispelling dampness; thus, for conditions of qi deficiency with damp-phlegm complicated by pathogenic invasion, it is miraculously effective. However, for qi deficiency with dry-phlegm complicated by pathogenic invasion, since Cangzhu is drying in nature, using it would only increase dryness. Consequently, the pathogen becomes more severe due to dryness, making it impossible to expel the pathogen. This is why treatment fails.

One might ask: Cangzhu's ability to induce sweating is far inferior to that of Baizhu, yet it is said that Baizhu stops sweating. Alas, the subtlety of Cangzhu lies entirely in its ability to induce sweating, surpassing Baizhu in this regard. All diaphoretic herbs disperse healthy qi to some extent. Although Cangzhu disperses qi when inducing sweat, it does so mildly. For deficient individuals contracting external pathogens who require wind-dispelling herbs, Cangzhu is preferable. This allows the pathogen to exit without significantly damaging healthy qi, and sweat to be released without excessive leakage of Yang qi. (Annotation: Cangzhu expels pathogens in cases of qi deficiency, actually surpassing other wind-dispelling herbs.)

One may suspect that Cangzhu's efficacy is far inferior to Baizhu, so why did the *Shennong Bencao Jing* not distinguish them? It is unknown whether Cangzhu and Baizhu were originally two distinct substances. Given the sage wisdom of Shennong, could he have been inferior to later generations? He must have distinguished them clearly. It is likely that due to the long passage of time and repeated wars and fires, records were lost. Today, through the elucidation of later scholars, it is evident that they cannot be used interchangeably for treating diseases. How then can they be used indistinguishably?

One might ask: Since Cangzhu and Baizhu have different natures, and Shennong failed to clarify them, there must be a reason. Your claim that they were lost over time seems like speculation rather than a definitive conclusion. Alas, Baizhu stops sweating while Cangzhu induces sweating; their effects are opposite and significant. How could such a vast difference exist without Shennong urgently pointing it out? Therefore, I believe he must have clarified them first before they were subsequently lost.