The goldsmith in your town writes out a note saying, I will pay to the bearer of this note so much gold, and then the bearer could be anyone.

你居住城镇的金匠写下票据并承诺,我会付给持票人这么多数量的金子,任何人都可以是持票人

耶鲁公开课 - 金融市场课程节选

The idea is that for any amount of money-- if this x is the amount of money that I receive-- utility as the function of the amount of money I receive is downwardly-concave.

这种观点是对于任何数量的货币,假设我得到x数量的货币,随着货币的增加,边际效用呈,向下凹进去的曲线

耶鲁公开课 - 金融市场课程节选