Name that quote

I'm reading Evolving Economics, a highly-regarded history of economic thought by Agnar Sandmo. I thought one tidbit early on was quite interesting: it comes in the course of a discussion of a once-common method of charging tolls based on the weight of carriages. Sandmo quotes an economist who recommended different rates for luxury versus other transport.

Thus, "...the indolence and vanity of the rich is made to contribute in a very easy manner to the relief of the poor, by rendering cheaper the transportation of heavy goods to all the different parts of the country."

Who said that? Answer below the fold...

Adam Smith, the patron saint of laissez-faire economists everywhere, in The Wealth of Nations no less. Sandmo comments, "This formulation is notable both for its substantial content and for the tone of its language, which leaves one with no doubt as to the author's sympathy and social concerns."