来自《耶鲁大学开放课程：金融理论 第5集 第5集》

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  utility of consuming today versus consuming tomorrow,
  给我们带来的效用是不同的
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  and let's say this utility is 1 half log
  我们假设对人A总效用为
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  So I'm going to come back to this in half an hour and explain
  我们一会儿回来讲
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  why Fisher thought that this half made sense.
  为什么这里要存在系数1/2
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  You see, this Agent A likes good 1 a lot more than good 2.
  我们看到人A喜欢1商品比2商品多
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  So Fisher would say that's because Agent A is inpatient.
  费雪认为人A是没有耐心的
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  An apple is an apple, but if you get it now it's
  同样是得到苹果
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  worth more to you, it gives you higher utility
  但是现在得到苹果的效用
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  than getting an apple next year.
  比明年得到苹果的效用大
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  "This is a law of human nature,"
  他说"这是人类的本性"
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  he claimed, which I'm going to come back to
  我们之后会回来讲这一点
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  later, and that's why when you write
  这就为什么我们在写效用方程的时候