(1) From _esteem values_ to _price equivalents_. The sum of money which a consumer would pay for the addition of an article to his possessions rather than go without that article is called its price equivalent. The price equivalent must not be confused with the price he may pay actually to buy the article, namely, the market price. A piano may have a market price of $600, but have a price equivalent of $1,000 to A. If the market price of pianos were to ascend to $1,000, A would still purchase one. But more than $1,000 he would not pay. When A assigns to a piano a price equivalent of $1,000, this sum of money, of course, has significance merely as the representative of the indefinite variety of other goods which A supposes to be within the command of $1,000. Thus A’s ability to think out price equivalents depends upon the already existing exchange value of money, or, in other words, upon prices themselves. If the market prices of carpets, carriages, wines and other things were different from what they are, the amount of other things commanded by $1,000 would be altered, and assuredly A’s price equivalent for a piano would change. Thus the price equivalent of one thing can be named only in view of previously existing scales of market prices of other things. A consumer comes to form a conception of the significance of a unit of money to his welfare. Into the question of the inner nature of this conception we cannot afford here to push our inquiry. Without this conception he could not set price equivalents. It is merely a matter of experience that in fact consumers do set price equivalents. The sole possible explanation of the fact that when a monopoly raises the price of a consumption good the sales of it decline, is that some buyers have been excluded because the price asked for has passed above their price equivalents.[222] The worth of money to a consumer depends upon the extent of his money income. Thus the price equivalent set upon a good by any consumer depends (1) upon the esteem value of that good to him, and (2) upon the extent of his money income. Given a consumer’s money income, his price equivalents for various articles will be determined by, and be in proportion to, the esteem values those articles have for him.