《论衡·卷十四·状留篇》
再说千里马一天能跑一千里，是没有负重，假使让它拉着装满东西的车子，跟劣马一样。
且骥一日行千里者，无所服也，使服任车舆，驽马同。
Moreover, a千里马 can run a thousand miles a day when unburdened, but if it is made to pull a carriage loaded with goods, it will be as slow as a bad horse.