《黄帝内经·灵枢·五色》
黄帝回答说：这是由于剧烈的邪气乘人体正气虚弱之时侵入脏腑，所以没有明显的疾病征象就突然死亡。
黄帝曰：大气入于脏腑者，不病而卒死矣。
The Yellow Emperor answered, "This is because evil qi, taking advantage of the body's qi being weak, invades the internal organs and that's why there are no obvious signs of a disease but a sudden death."