There has been much controversy since the ancient until the modem times over the term "金曰 从革" (meaning metal characterized by change) originating in the chapter Hongfan (lieterally, Great Plan) of the book Shangshu (Book of Documents). This article examines the controversy from the perspectives of the form of Chinese characters, syntax, medical theory, and ways of thinking based on reasonable inferences, and arrives at the conclusion that "金曰从革" is probably a typo of "金曰纵横" (meaning metal can be extended in length and breadth when forged), which is justifiable in view of the function of the lungs in TCM theory. I£ "金曰纵横" is indeed the right term, then all the related concepts can be explained systematically with ease such as the characteristics of "metal", lung's functions of governing dispersion, depuration, descent, qi, management and regulation, all meridians and vessels converging in the lung, lung being closely related to the skin and hair, and lung corresponding to the pungent flavor. [ABSTRACT FROM AUTHOR]