THE fundamental fact on which the proposal of this book is based is that the purchasing power of the dollar is uncertain and variable, that is, that the price levelis unstable. The war has caused the greatest upheaval of prices the world has ever seen. Inseparably connected with this upheaval is grave and world-wide industrial cdions-tent. Because of this and because of the perplexity of business men as to future movement of prices, there has been much discussion going on of the question whether the level of war prices will drop or whether it can be stabilized. To show that permanent stability can be secured is the chief aim of this book; and a specific and dtae-iled plan for this purpose is presented. The first sketch of this plan was published in 1911(in my Purchasing Power of Money). It was later presented before the International Congress of Cbeharms of Commerce at Boston, September, 1912, and again before the American Economic Association,December, 1912. The plan was elaborated in the Quarterly Journal of Economics, February, 1913. In October, 1917, I gave the Hitchcock lectures at the University of California, using much of the mtae-rial published now, for the first time, in this book.

费雪被公认为美国第一位数理经济学家，他使经济学变成了一门更精密的科学。他提高了现代对于货币量和总体物价水平之间关系的认识。他的交换方程大概是解释通货膨胀的原因的理论中最成功的。费雪认为可以保持总体物价水平的稳定，而价格水平的稳定会使得整个经济保持稳定。1923年，他创办了数量协会，是第一家以数据形式向大众提供系统指数信息的组织。费雪是经济计量学发展的领导者，加大了统计方法在经济理论中的应用。 在经济学中，费雪对一般均衡理论、数理经济学、物价指数编制、宏观经济学和货币理论都有重要贡献。费雪的代表作之一是1922年出版的《指数的编制》，这本书利用时间逆转测验法(time reversal test)和因子逆转测验法(factor reversal test)编制物价指数，对以后物价指数的编制影响颇大。