When the ancients drank tea, they should not only pay attention to water quality, but also pay attention to tea quality. These two sentences, first, refer to the use of spring water in the middle reaches of the Yangtze River (named Zhong Ling Spring) to make tea, with excellent water quality; The second is the excellent quality of Mengding tea. It shows that Sichuan tea represented by Mengding tea at that time had the longest history, the largest output and the highest status of tribute tea.