《汉书·志·五行志中之下》
有人解释说：凡是不成灾的事情都不记载，衹记严重的事情，即造成灾害的。
说曰： 凡物不为灾不书，书大，言为灾也。
Some have interpreted it as follows: All things that do not become disasters are not recorded, and only serious things, i.e., those that cause disasters, are recorded.