分久必合，合久必分
fēn jiǔ bì hé，hé jiǔ bì fēn
基本释义
  1. 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。”
英文翻译
  1. fig. things are constantly changing
  2. lit. that which is long divided must unify, and that which is long unified must divide (idiom, from 三国演义)