Xia San month. The three months in summer are the so-called "vegetation show", which is a season of beautiful reproduction. In the meantime, the yin and yang of heaven and earth interact, and plants also blossom and bear fruit, which is in line with the way of staying up at night and getting up early and being insatiable. Going to bed late and getting up early means that people should stay up late and get up early, and don't hate that the days are too long, so that there will be no depression and anger in their hearts, and their faces will look good, which makes sense of the heat in summer. Show the beauty outside. This is an echo of "fitness" in summer. If you violate this principle, your heart will be hurt, you will get malaria in autumn, your supply capacity will be poor in autumn, and you will get seriously ill in winter.