《汉书·志·食货志下》
到管仲辅佐齐桓公，通行了轻重的衡量标准，他说： 年岁有荒年和丰收之年，所以谷有贵有贱；命令有慢有急，所以货物有轻有重。
至管仲相桓公，通轻重之权，曰： 岁有凶穰，故谷有贵贱；令有缓急，故物有轻重。
When Guan Zhong assisted Qi Huangong, he applied the standard of measuring the weight, and he said: there are years of famine and years of harvest, so the price of grains fluctuates; there are times when the orders are urgent and times when the orders are slow, so the weight of goods varies.