From Su Shi's (
苏轼, Northern Song) 《
水调歌头·
明月几时有》, written at Mid-Autumn 1076 for his brother Su Zhe:
人有悲欢离合,
月有阴晴圆缺,
此事古难全 — 'People know sorrow and joy, parting and reunion; the moon is dark or bright, full or waning — such has been the incompleteness of things since ancient times.' One of the most quoted couplets in all of Chinese literature.