What does it mean to be green and ancient?

Refers to the solar terms in Tomb-Sweeping Day and Grain Rain. Valley-clearing Day comes from the 24 solar terms Song Dynasty: Spring rains startle Spring Valley-clearing Day, and summer mountains are connected with summer heat. Autumn dew, autumn frost, little snow in winter and cold in winter. The first half of the year is June 2 1 day, and the second half is August 23. The two festivals remain unchanged every month, with a maximum difference of one or two days. "Spring rain begins with spring, and the valley clearing day" refers to beginning of spring, rain, fright, vernal equinox, Qingming and Grain Rain in spring.

Tomb-Sweeping Day and Grain Rain solar terms. Valley-clearing Day comes from the 24 solar terms Song Dynasty: Spring rains startle Spring Valley-clearing Day, and summer mountains are connected with summer heat. Autumn dew, autumn frost, little snow in winter and cold in winter. The first half of the year is June 2 1 day, and the second half is August 23. The two festivals remain unchanged every month, with a maximum difference of one or two days.

"Spring rain begins with spring, and the valley clearing day" refers to beginning of spring, rain, fright, vernal equinox, Qingming and Grain Rain in spring.

"Summer is full and Xia Xia is connected" refers to the long summer, the little summer, the boundless middle summer, the summer solstice, the little summer and the big summer.

"Autumn dew and autumn frost" refers to beginning of autumn, summer, white dew, autumnal equinox, cold dew and first frost in autumn.

"Winter snow and winter slight cold" refers to the beginning of winter, with light snow, heavy snow, winter solstice, slight cold and severe cold.