《战国策·韩三·韩人攻宋》
秦王说： 我本来就担心齐国的行动难以意料，一会儿合纵一会儿联横，你又这样说，为什么？ 
秦王曰： 吾固患韩之难知，一从一横，此其说何也? 
The king of Qin said: I was worried that Qi's move was unpredictable, sometimes uniting vertically and sometimes uniting horizontally. Why do you say that?