"Price is not the same thing as value. Suppose that on a day the price of everything viz., coal, bread, postage stamps, a day's labour, the rent of houses, etc. were to double. Prices then would certainly rise, but-values of all things except one would not." The writer wants to say that if prices of all things were doubled

The core idea is the distinction between price (a monetary expression) and value (purchasing power or relative worth). 1. If the prices of *all* goods and services (coal, bread, labour, rent, etc.) double, it means that the relative worth of these goods and services to each other remains unchanged. For example, if a loaf of bread and a day's labour both double in price, a day's labour still buys the same number of loaves of bread. So, the "values of all things except one would not" change refers to the relative values of goods and services to each other. 2. The "one" thing whose value *would* change is money itself. If everything costs twice as much, then each unit of money (e.g., a rupee, a dollar) can now buy only half of what it could before. Its purchasing power has been halved. Analyzing the options: A) the values of all things would remain constant - Incorrect. The value of money would change. B) the values of the things sold would be doubled - Incorrect. Their relative values to other goods remain constant. Their price in money doubles, but not their value in terms of other goods. C) the values of the things bought would be halved - Incorrect. Similar to B, relative values remain constant. D) the value of money only would be halved. - Correct. Since all prices double, money can now buy only half the quantity of goods and services it previously could. Its purchasing power, and thus its value, is halved.