《尔雅·释虫》∶ 、白鱼。郭璞注∶今衣书中虫，一名 鱼，《别录》及《图经》、《千
金翼方》，亦同。《千金方》、《外台秘要》，或曰衣中白鱼，或曰书中白鱼，又单称白鱼。虽
然，《本经》未尝以白鱼为本名，则古方所谓白鱼者，是必鱼部白鱼，非衣书中白鱼矣。况
又虫而得鱼名者，以其形稍似鱼，其尾又分二歧，故得 及 鱼、蠹鱼之名。虽然，但不可
单以白鱼为本称也。后之用此者，能治小便不利，则益以衣中白鱼为古方白鱼矣。滑石白鱼
散证曰∶小便不利。此方本载于《金匮要略》小便利淋篇内，则盖淋家小便不利者主之。本
草∶衣鱼，主治小便不利。《别录》疗淋，附方又载此方，主治小便不通。然则诸家皆以衣
鱼为白鱼，明矣。虽然，此方内白鱼，未可知衣中白鱼否，并存此二物，以俟后之考订试效。
凡药方内，有不以本名称，而以异名呼之者，不欲使人知其物也，是皆后世医家之陋也。
独仲景之方，无以异名称之者，如彼乌头、附子、天雄，则以其年数形状称之；如彼芒硝、
硝石、朴硝。则以其制之精粗，功之缓急取之；如彼白 酒、浆水，则以诸家所称之名呼之，
或以诸家所传之方录之，盖无异义。按仲景撰用诸家之方，未尝变其方名，根据其所称而取之
耳。然则如此白鱼散，当须根据其本名矣。由是观之，白鱼者，盖非衣中白鱼明矣。明者其审
诸。
*Er Ya · Shi Chong* records: "Jue, Bai Yu (White Fish)." Guo Pu commented: "It is the insect found in clothes and books today, also named Jue Yu. *Bie Lu* (Additional Records of Materia Medica), *Tu Jing* (Illustrated Classic of Materia Medica), and *Qianjin Yi Fang* (Supplement to Essential Prescriptions Worth a Thousand Gold) all agree." In *Qianjin Fang* (Essential Prescriptions Worth a Thousand Gold) and *Waitai Miyao* (Secret Essentials of the Outer Cabinet), it is sometimes called "Yi Zhong Bai Yu" (White Fish in Clothes), sometimes "Shu Zhong Bai Yu" (White Fish in Books), or simply "Bai Yu" (White Fish). Nevertheless, *Ben Jing* (Shennong's Classic of Materia Medica) never used "Bai Yu" as its primary name. Therefore, the "Bai Yu" mentioned in ancient prescriptions must refer to the White Fish from the fish family, not the White Fish found in clothes and books. Moreover, insects that bear the name of fish do so because their shape somewhat resembles a fish, and their tails are bifurcated; thus, they are named Jue, Jue Yu, and Du Yu (Bookworm). Even so, one cannot use "Bai Yu" alone as its formal name. Later users of this substance, noting its ability to treat difficult urination (Xiao Bian Bu Li), further identified the Yi Zhong Bai Yu as the Bai Yu of ancient prescriptions. The indications for Huashi Bai Yu San (Talcum, White Fish, and Lygodium Spores Powder) state: "Difficult urination." This prescription was originally recorded in the chapter on Normal Urination and Stranguria in *Jin Gui Yao Lue* (Essential Prescriptions of the Golden Cabinet); thus, it is likely intended for patients with stranguria (Lin Jia) who suffer from difficult urination. Materia Medica records: "Yi Yu (Clothes Moth) treats difficult urination." *Bie Lu* states it treats stranguria, and the attached formulas record this prescription for treating complete inability to urinate. Consequently, various authorities have equated Yi Yu with Bai Yu, which is clear. However, regarding the "Bai Yu" in this formula, it is uncertain whether it refers to the Yi Zhong Bai Yu. Both substances are preserved here for future verification and efficacy testing.
In medicinal formulas, when a substance is referred to by an alias rather than its proper name, it is often to conceal its identity; this is a flaw of later physicians. Only the formulas of Zhang Zhongjing did not use aliases. For instance, Wu Tou (Aconite Root), Fu Zi (Prepared Aconite Root), and Tian Xiong (Lateral Root of Aconite) were named according to their age and shape; Mang Xiao (Mirabilite), Xiao Shi (Niter), and Pu Xiao (Saltpeter) were distinguished by the refinement of their processing and the urgency of their effects; Bai Jiu (White Wine) and Jiang Shui (Sour Rice Water) were referred to by the names used by various schools or recorded from transmitted formulas, without any hidden meaning. Examining the formulas Zhang Zhongjing adopted, he never altered their original names but selected them based on the names given by others. Therefore, for a formula such as Bai Yu San, one must determine the ingredient based on its proper name. From this perspective, it is evident that "Bai Yu" does not refer to the Yi Zhong Bai Yu. Those who understand this should examine it carefully.