《黄帝内经·素问·阴阳应象大论》
西方属阴，阴性向下，向下则下盛而上虚，所以对应于人体则耳目不聪明而手足便利。
西方阴也，阴者其精并于下，并于下则下盛而上虚，故其耳目不聪明而手足便也。
The west is considered shady, the shady nature moves downwards, when it moves downwards, it is strong at the top while hollow at the bottom, so when corresponding to the human body, the ears and eyes are not as clever while the hands and feet are convenient.