Which solar term does Chinese medicine call long summer?

There are many explanations, some say it is the last month of summer, that is, June of the lunar calendar, some say it is the last18th day of each season, and some say it is the period from beginning of autumn to the autumnal equinox.

In the written records before Neijing, there is no concept of "long summer", only "late summer month". For example, The Book of Rites: "In late summer and June, the Duke of Zhou offered a ceremony to the temple."

"Spring and Autumn Stories Five Elements Pair" also records: "There are five elements in the sky, including wood, fire, earth and gold. Wood fires, fire produces soil, soil produces gold, and gold produces water. Water is winter, gold is autumn, soil is the last month of summer, fire is summer and wood is spring. Spring is the main life, summer is the main growth, and late summer is the main cultivation, autumn is the main harvest, and winter is the main storage. "

"Moon at the end of summer" is a concept belonging to the theory of five elements before the appearance of Neijing. When the author of Neijing introduced the theory of five elements into medicine, he changed "late summer month" to "long summer". Therefore, there is a saying in later generations that "the end of summer is a long summer".

Later generations have Bing Wang, Zhang Zhicong and others to collate Neijing, but the definition of "Xia Long" is still inconclusive. Long summer, as an important season, has not been clearly defined in time, which leads to the popularity of various versions of definitions and the confusion of division.