ko나는 산 사람의 일은 헤아릴 수 있어도, 죽은 사람의 일은 헤아릴 수 없지 않은가.
ja私は生きている者のことは読めても、死んだ者のことまでは読めぬではないか。
The scene behind the words
Told of the taunt "dead Kongming routed living Zhongda" after his hasty withdrawal at Wuzhang Plains, Sima Yi laughed and turned it aside with this line. The wit that converts humiliation into logic is itself the measure of the man — the composure of the war’s final winner, even before his great rival’s corpse.
Source: Han Jin Chunqiu (annotations to Zhuge Liang’s biography)