Where did the poetic aestheticism in March spring come from?

1. In February and March, the grass is the same color as the water. -"Danyang Mengzhu Song" Mengzhu [Northern and Southern Dynasties].

2. on the third day of the Third-month in the freshening weather, many beauties take the air by the Changan waterfront. -"two for the road" Du Fu [Tang].

3. Budeze in Yangchun makes everything shine. -"Long Songs" Han Yuefu.

4. In February and March in Xianyang, the golden branches of the palace willows. -"Antique" Li [Tang].

5. The grass and trees know that spring will come back soon, and all kinds of flowers are fighting for the grass. -"Late Spring" Han Yu [Tang].