《管子·匡君小匡》
他们负任担荷，赶牛驾马，以周游四方；料定物资多寡，估计商品贵贱，以其所有，易其所无，贱买贵卖。
负任担荷，服牛辂马，以周四方；料多少，计贵贱，以其所有，易其所无，买贱鬻贵。
They carry burdens, drive cattle, and ride horses to travel everywhere; they estimate the quantity of goods, estimate the price of commodities, use what they have to exchange for what they do not have, and buy low and sell high.