指人或事物变化无常，分合无定。
出处：《三国演义》第一回话说天下大势，分久必合，合久必分。”
例句：这也是～的天下定理。★《雪岩外传》第十二回
分久必合，合久必分 fēn jiǔ bì hé，hé jiǔ bì fēn
| 拼音 | fēn jiǔ bì hé，hé jiǔ bì fēn |
|---|---|
| 英文 | (lit.) that which is long divided must unify, and that which is long unified must divide (proverb, from Romance of the Three Kingdoms 三國演義|三国演义[San1 guo2 Yan3 yi4]); (fig.) things are constan |