出陕西州郡及河阳。其木似檀。枝干皆青绿。叶细如匙。虚大不光。并无花实。皮上有
白点。
味苦。气寒微。沉也。降也。入足厥阴少阳经。 大戟为之使。恶吴茱萸。 主治风寒
湿痹洗洗寒气。（如冷水浇）洗肝益精。除热。疗目中青翳白膜。去两目赤肿疼痛。久热风
泪不止。治热痢下重。下焦虚。疗妇人崩带。作汤浴小儿惊痫风热。秦皮水浸。即青碧。青
入肝。风邪为病。先见于色。当为肝之风药。
〔论〕 本经秦皮首主风寒湿痹。洗洗寒气除热。是所谓除热者。即其散风寒湿之痹。
不致郁而为热也。继云疗目中青翳白膜。夫东垣论青白翳有曰。阴盛阳虚。则九窍不通。令
青白翳见于大 。乃足太阳少阴经中郁遏。厥阴肝气。不得上通于目。故青白内阻也。以此
相证。则秦皮退热之功。不专散肝经之风寒湿痹哉。日华子定其用曰洗肝。为能祛寒水之阴
以达阳。不致郁而为热。得还其敷和之平气也。故伤寒传经至厥阴。仲景用此为主药。可谓
得先圣之精诣矣。（传经之热。正因寒郁。）别录疗男子少精。妇人带下。何以明之。张子和
曰。冲任督三脉。同起而异行。一源而三歧。皆属带脉。因诸经上下往来。遗热于带脉之间。
客热郁抑。遂致白物淫溢。男子因溲而下。女子绵绵而下也。经曰。带脉起于季肋足厥阴之
章门穴。同足少阳循带脉穴。围周一身。如束带然。若是。则带下之病。焉得不取责于肝乎。
夫冲任督皆本于肾。皆以肝行其化。秦皮达其阴之郁阳者。即能祛其阳之伤阴者。如带下之
疗。在除湿热。即本经达风寒湿痹之气。而便以除热之治也。粗工漫同苦寒之味言其退热。
岂知本经止言其气微寒。而甑权又言气平。不依然敷和之春气哉。至于男子益精。当思冲任
督俱起于肾。俱行化于肝。以默识此味之功矣。经曰。两神相搏谓之精。两神者。阴阳二气
也。肝以一阴为独使。下合于任。上会于督。阴阳之相搏 也。岂其微哉。（肝得行其化。
则阴中之阳。所谓元气者自盛。气盛则精盈。修真家亦是此理。）
〔辨治〕 去骨取皮。渍水。水色侵碧。书纸纸面略青者真。
Qinpi (Fraxinus Cortex) originates from various prefectures in Shaanxi and Heyang. Its wood resembles that of sandalwood, with branches and trunks all appearing greenish-blue. The leaves are slender like spoons, loose and large but not glossy, lacking flowers and fruits. There are white spots on the bark.
It tastes bitter and has a slightly cold nature. It is heavy and descending, entering the Foot-Jueyin Liver Meridian and Foot-Shaoyang Gallbladder Meridian. Dajixie (Radix Euphorbiae Pekinensis) serves as its guiding herb. It is incompatible with Wuzhuyu (Fructus Evodiae).
It primarily treats Bi syndrome caused by wind-cold-dampness, characterized by a chilling sensation (as if cold water were poured on the body). It clears the liver, benefits essence, eliminates heat, treats green nebula and white membrane in the eyes, removes redness, swelling, and pain in both eyes, and treats persistent tearing due to chronic wind. It treats dysentery with tenesmus, deficiency of the Lower Jiao, leukorrhea and metrorrhagia in women, and pediatric convulsions and wind-heat when decocted for bathing. When Qinpi is soaked in water, the water turns blue-green. Blue enters the Liver; since wind-pathogens manifest first in complexion, Qinpi should be regarded as a herb treating Liver wind.
[Discussion] The *Shennong Bencao Jing* states that Qinpi primarily treats Bi syndrome due to wind-cold-dampness, eliminating chilling sensations and clearing heat. The so-called "clearing heat" refers to dispersing the obstruction of wind-cold-dampness, preventing it from stagnating and transforming into heat. It further mentions treating green nebula and white membrane in the eyes. Li Dongyuan discussed green and white nebulae, stating: "When Yin is excessive and Yang is deficient, the nine orifices become blocked, causing green and white nebulae to appear in the eyes. This is due to stagnation in the Foot-Taiyang Bladder Meridian and Foot-Shaoyin Kidney Meridian, where the Qi of the Jueyin Liver cannot ascend to the eyes, thus obstructing the interior with green and white pathogenic factors." Corroborating this, the heat-clearing efficacy of Qinpi is not limited to merely dispersing wind-cold-dampness Bi in the Liver Meridian. Ri Huazi defined its function as "washing the liver," meaning it dispels the Yin of cold-water to reach Yang, preventing stagnation and transformation into heat, thereby restoring the harmonious and mild Qi of the Liver. Therefore, when Typhoid fever transmits to the Jueyin stage, Zhang Zhongjing used this herb as the principal ingredient, truly mastering the profound insights of the ancient sages. (The heat transmitted via meridians is precisely due to cold stagnation.) The *Mingyi Bielu* records its treatment of scanty essence in men and leukorrhea in women. How is this explained? Zhang Zihe said: "The Chong, Ren, and Du meridians originate from the same source but diverge in their pathways; they form one source branching into three, all belonging to the Dai Meridian. As the various meridians travel up and down, they leave residual heat within the Dai Meridian. Guest heat stagnates, leading to an overflow of white discharge, which exits through urination in men and flows continuously in women." The classics state: "The Dai Meridian originates at Zhangmen (LR13) on the hypochondrium of the Foot-Jueyin Liver Meridian, running along the Daibao point of the Foot-Shaoyang Gallbladder Meridian, encircling the body like a belt." In this manner, how can leukorrhea not be attributed to the Liver? The Chong, Ren, and Du meridians originate from the Kidney and undergo transformation via the Liver. Qinpi unblocks the stagnant Yang within Yin, thereby dispelling the Yang heat that damages Yin. For instance, treating leukorrhea involves removing damp-heat, which aligns with the *Bencao Jing*'s description of unblocking wind-cold-dampness Bi to achieve heat clearance. Crude practitioners casually attribute its heat-clearing effect to its bitter-cold taste, failing to realize that the *Bencao Jing* only describes its nature as slightly cold, and Zhen Quan described it as neutral, consistent with the harmonious spring Qi. Regarding benefiting essence in men, one must consider that the Chong, Ren, and Du meridians originate in the Kidney and transform in the Liver, thereby understanding the merit of this herb. The classics say: "The interaction of two spirits is called Essence." The two spirits refer to Yin and Yang Qi. The Liver acts as the sole envoy of Yin, connecting downward with the Ren Meridian and upward with the Du Meridian. The interaction of Yin and Yang is significant. (When the Liver functions properly, the Yang within Yin, known as Yuan Qi, becomes robust; robust Qi leads to abundant Essence, a principle also recognized in Daoist cultivation.)
[Differentiation and Treatment] Remove the woody core and use only the bark. Soak in water; if the water turns blue-green and writing on paper results in a slightly bluish surface, it is authentic.