《晋书·志·第二章》
凡游动天气遮蔽苍天，日月失色，都是是风雨的徵候，阴阴沉沉，日月都没有光辉，白天不见太阳，夜晚不见星星，有云障蔽着，是两敌相当，暗暗彼此图谋。
凡游气蔽天，日月失色，皆是风雨之候也，沈阴，日月俱无光，昼不见日，夜不见星，有云障之，两敌相当，阴相图议也。
In general, when wandering weather obscures the heavens, causing the sun and moon to lose their brightness, these are all signs of wind and rain; when it is always cloudy and gloomy, and there is no brightness from the sun or moon, during the day when there is no sun, and at night when there are no stars, and when there are clouds obscuring everything, it is a sign that two enemies are evenly matched and plotting against each other in secret.