What do you mean, four unique days?

The day before beginning of spring, Changsha, beginning of autumn and beginning of winter take four days off is called four days off. According to ancient China, water (winter) will be extinct when spring begins and comes back, and wood (spring) will be extinct when it gets hotter in the long summer. When it gets cold in early autumn the day after tomorrow, the fire (summer) goes out, and when it gets cold in early winter the day after tomorrow, the gold (autumn) goes out. Therefore, the day before the establishment of the four pillars is called four days.

Introduction:

Among the 24 solar terms throughout the year, the day before the vernal equinox, autumnal equinox, summer solstice and winter solstice is four days away from the sun. Four days from the sun, ten days in a quarter, the ancients concluded that it was unlucky; Among the 24 solar terms of the four seasons, the day before beginning of spring, Changxia, beginning of autumn and beginning of winter is the four seasons. Four parting is the beginning of four seasons, and four unique seasons are the end of four seasons. The ancients were afraid of exhaustion and decided it was unlucky. Therefore, it is generally useless not to choose this day to do great things in Li Si and Spyker's Day. It is the day when the new official takes office and the old official abdicates. Generally, no one cares about bad luck, which can be used to transfer jobs.