Why is the hottest day in summer called "dog days"?

The "dog days" are determined according to the ancient "sun and branches tracking method" in China. The method of "recording the date by branches" is a method of recording the date sequence by branches. The trunk branches are the ten-day trunk branches of A, B, C, D, E, Ji, Ke, Xin, Ren and Gui, and the twelve-day trunk branches of Zi, Ugly, Yin, Mao, Chen, Si, Wei, Shen, You, Xu and Hai. Like the chronology of dry branches, the chronology of dry branches records the date series of 60 Jiazi matched with the chronology of dry branches, from Jiazi to Guihai, with a cycle of 60 days.

Every year from long summer to the future, the third Geng Day (referring to the day with the word "Geng") is the first day, the fourth Geng Day is the first day, and the first Geng Day after beginning of autumn is the last day, which is collectively called "three days".

Geng Day is repeated every 65,438+00 days, so the initial lodging is 65,438+00 days, the intermediate lodging is 65,438+00 days or 20 days, and the final lodging is 65,438+00 days.

Why is there a difference between 10 and 20 days in the middle range? This is because if there is only one Geng day between the summer solstice and the beginning of autumn, the middle part is 10 days, and if there are two Geng days, it is 20 days.

When the mid-range was 20 days, the average person called it four days, and now it is still three days, but the mid-range is longer.

What does "v" mean? In the hottest days of summer, the spirit of the sun reached its peak, and then it turned from prosperity to decline, ushered in cool autumn weather. At this time, the heat of the sun completely enveloped the yin, so the yang was flourishing and the yin was hidden. Therefore, the "fu" in the dog days means that the yang is full and the yin is hidden. In dog days, people always feel sweating all over, but the name of dog days already contains the waiting and association for shade.

Summary: "Winter disease is cured in summer". People with yang deficiency or yin deficiency can eat mutton and stick it in the dog days in the hottest summer, so that the body can use the heat of external yang and drugs to force out the cold evil hidden in the body and achieve the purpose of treatment.

Dog days are the hottest days of the year, and so are the hottest days in dog days. At this time, people want to enjoy the cool, schools have summer holidays, and ancient private schools also have holidays, which is called "Summer Festival".