"" was recorded in Liu Jie Zang Xiang Lun of Su Wen (《·》, On Six-Period and Visceral Manifestation of Plain Questions), and there has been 11 versions of interpretation on "Pi Ji ()" in last 400 years since Wu Kun of the Ming dynasty. "Pi Ji ()" appeared 3 times in Xuanquan Han slips, annotated as "Pi Ji ()" , denoting " (fatigue)" , a synonymous compound word. "Pi Ji ()" was seen on 9 occasions in Shi Ji (《》, The Historical Records) and Han Shu (《》, History of The Former Han) altogether, with the annotation of "Pi Kun (fatigue and tiredness)" by Yan Shigu. It is confirmed that the "Pi Ji ()" means " (fatigue)" and the "" can thus be interpreted as "Liver is the root of utmost exhaustion or fatigue" , with a combination of evidence from excavated texts and existing literature records supported by clinical and experimental data.
《素问·六节藏象论》述有"肝者罢极之本"，如何解读"罢极"，从明代吴崑至今，聚讼400余年，观点可达11种；《悬泉汉简》三见"罢亟"，注为"罢极"，义为"疲劳"，同义复词。《史记》《汉书》九见"罢极"，颜师古注为"疲困" ，结合出土文献、传世文献、临床、实验之据，确证"罢极"即为"疲劳" ， "肝者罢极之本"即为"肝者，疲劳之本" 。.
Keywords: Pi Ji; Xuanquan Han Slips; the root of Pi Ji.