A transaction involving potatoes happens at one point in time only: the buyer parts with her money, the seller parts with his tubers, and that is it. A financial transaction, by contrast, happens over time: the borrower gets the money today and promises to repay in a month, year, or decade.
土豆交易只在某一个时点发生：买家交钱，卖家交货，交易完毕。相反，金融交易需要一段时间：借款人今天拿钱，承诺一个月、一年或十年后偿还。这让金融十分容易受到流氓和骗子的青睐。而由于对未来事件的预期和信心具有关键重要性，因此政府必须向欧洲央行行长德拉吉那样时刻准备着“不惜一切代价”稳定金融市场。