《元史·列传·卷九十二》
往时富民于国外经商，多获厚利。商人越多，则中国货价值不高，而外国货反而贵重。
又往时富民，往诸蕃商贩，率获厚利，商者益众，中国物轻，蕃货反重。
In the past, wealthy citizens made large profits from overseas trade. The more merchants there were, the cheaper the prices of Chinese goods became, while the prices of foreign goods became more expensive.