If you look at the percent of time people in society were involved in various activities and broken into agriculture versus everything else, in ancient Egypt it looked like this.

如果你留意一下,人们从事各种社会活动的时间比例,被分为农业生产和其他活动两类,在古埃及,时间分配是这样的

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

Your mortgage payment is constant through time but the fraction of it that goes to paying off principal versus interest changes through time and it just changes as dictated by this formula.

抵押贷款每月还款是固定的,但是其中本金和利息的比例关系,会随时间而改变,这是由这个公式所决定的

耶鲁公开课 - 金融市场课程节选