They had to cooperate with other people that they owe a debt to society and that that's expressed in taxation.

必须与他人合作,所以他们欠社会的,所以要用纳税来还。

耶鲁公开课 - 公正课程节选

Suppose you are interested in investing in debt of companies, then you as an investor are subject to the problem that you might end up with the worst stuff if you don't watch out.

假设你有兴趣投资于公司债权,那么作为投资人你会面临这样一个问题,如果不谨慎,投资有可能会血本无归

耶鲁公开课 - 金融市场课程节选