人间正道是沧桑

The final line of Mao Zedong's 1949 七律 poem 《七律·人民解放军占领南京》 (Seven-Character Regulated Verse: The PLA Occupies Nanjing), written the day after Communist forces took the Nationalist capital: 天若有情天亦老，人间正道是沧桑 - 'Were Heaven sentient, it too would grow old; the true path of the human world is cataclysmic change.' 沧桑 is short for 沧海桑田 ('blue seas become mulberry fields') - monumental transformation.

Often quoted in political and historical commentary. Also the title of a popular 2009 CCTV drama about a family across 20th-century Chinese history.