《棋经十三篇·合战篇》
凡是对手无缘无故地自行补救时，就表明他意在进犯突袭；放弃局部的棋子不救时，就表明他意在争夺大局的优势。
凡敌无事而自补者，有侵袭之意也。弃小而不救者，有图大之心也。
Whenever an opponent suddenly makes a move to save a position for no reason, it means that he intends to attack and raid; when an opponent gives up a local piece and does not save it, it means that he intends to fight for an advantage in the big picture.