Mencius - Book 3, Part 1, Chapter 4H

Ch'an Hsiang said, 'If Hsü's doctrines were followed, then there would not be two prices in the market, nor any deceit in the kingdom. If a boy of five cubits were sent to the market, no one would impose on him; linen and silk of the same length would be of the same price. So it would be with bundles of hemp and silk, being of the same weight; with the different kinds of grain, being the same in quantity; and with shoes which were of the same size.'

Mencius replied, 'It is the nature of things to be of unequal quality. Some are twice, some five times, some ten times, some a hundred times, some a thousand times, some ten thousand times as valuable as others. If you reduce them all to the same standard, that must throw the kingdom into confusion. If large shoes and small shoes were of the same price, who would make them? For people to follow the doctrines of Hsü, would be for them to lead one another on to practice deceit. How can they avail for the government of a State?'
~ James Legge translation via nothingistic.org ~

Go here to read the introductory post to this serialized version of the Works of Mencius.