In its long history

tongue diagnosis progressed at a slow pace during its early and middle development. Back then

the term for this concept was but ‘She（ 舌

tongue） ’or ‘Sheshangtai（ 舌上胎

embryo upon the tongue） ’. Not until Yuan Dynasty was the first treatise on this issue published

where the saying of ‘Shetai（ 舌胎

tongue embryo） ’was proposed. In the mid-Ming Dynasty

tongue diagnosis began to receive extensive attention. At that time

its application was mostly limited to the diagnosis of Shanghan（ 伤寒

cold pathogenic diseases）. In the late Ming dynasty

WU Youke initiated its usage as a method to diagnose Wenbing（ 温病

warm pathogenic diseases）. In the early Qing Dynasty

LU Zhiyi proposed the saying of ‘Shetai（ 舌苔

tongue coating） ’. His effort was followed by YE Tianshi and other doctors of Wenbing school

who applied tongue diagnosis in a broader way

making it developed to a new level. WU Jutong was the first to distinguish ‘Shetai（ 舌胎

tongue embryo） ’and ‘Shetai（ 舌苔

tongue coating） ’. He emphasized that the growth of the tongue coating is similar to the moss in the shady area

hence his emphasis was put on Rou（ 肉） rather than Cao（ 草）. This point influenced many other doctors. From then

‘Shetai（ 舌苔

tongue coating） ’gradually replaced ‘Shetai（ 舌胎

tongue embryo） ’. Using ‘You Gen（ 有根

presence of roots） ’and‘Wu Gen（ 无根

absence of root） ’in‘Shetai（ 舌苔

tongue coating） ’to differentiate between excess and deficiency had been widely applied in clinical diagnosis for Wenbing. Its application was further extended to surgical and internal medicines in TCM during the mid-Qing Dynasty with the presence of a large amount of relevant treatises. ‘Shetai（ 舌胎

tongue embryo） ’and ‘Shetai（ 舌苔

tongue coating） ’finally developed into distinct concepts

reflecting the developments of tongue diagnosis in different periods.