分久必合，合久必分

[fēn jiǔ bì hé，hé jiǔ bì fēn]

[ fēn jiǔ bì hé ， hé jiǔ bì fēn ] 指人或事物变化无常，分合无定。

《三国演义》第一回话说天下大势，分久必合，合久必分。”

这也是～的天下定理。★《雪岩外传》第十二回

fig. things are constantly changing; lit. that which is long divided must unify, and that which is l