Summer solstice and autumnal equinox, spring to winter, solstice is written by Yang Ningshi, a poet in the Tang Dynasty. Yang Ningshi, a native of Shaoling, was a famous writer, calligrapher and politician in the middle Tang Dynasty. He is one of the important figures in the literary history of the Tang Dynasty, and is known as "the poet saint of the Tang Dynasty", and is also called "Du Yang" with Du Fu. Yang Ningshi's poems are fresh and refined in style, profound in artistic conception and of high artistic value. His representative works include Ascending the Mountain and Farewell to Ancient Grass. Yang Ningshi was also a famous calligrapher in the Tang Dynasty. He is good at official script and running script, which has a great influence on the development of calligraphy in later generations.