expression
the world is in constant flux; the blue sea turns into a mulberry field
A classical yojijukugo expressing that the world undergoes dramatic changes over time, often used in literary or philosophical contexts. The literal image is of the sea transforming into farmland.
滄海桑田の言葉通り、世の中は絶えず移り変わっている。
As the saying goes, the world is constantly changing.
From classical Chinese literature; the phrase originally describes the transformation of a blue sea into a mulberry field, symbolizing great changes over time.