… is from Book IV, Chapter 3  – on page 493, Vol. 1, of the 1981 Liberty Fund edition  – of Adam Smith’s 1776 An Inquiry Into the Nature and Causes of the Wealth of Nations :
That it was the spirit of monopoly which originally both invented and propagated this doctrine [mercantilism] cannot be doubted; and they who first taught it were by no means such fools as they who believed it. In every country it always is and must be the interest of the great body of the people to buy whatever they want of those who sell it cheapest. The proposition is so very manifest that it seems ridiculous to take any pains to prove it; nor could it ever have been called in question had not the interested sophistry of merchants and manufacturers confounded the common sense of mankind. Their interest is, in this respect, directly opposite to that of the great body of the people.
One of the most impressive pieces of cunning ever perpetrated is the product of the chicanery of many private business people. They and their spokes-legions routinely dupe the economically misinformed masses (and especially those members of the economically misinformed masses who fancy themselves to be unusually smart, caring, progressive, and well-informed) into believing that socially harmful and archaic policies that in fact artificially raise the profits of particular businesses at the general expense of consumers, workers, and taxpayers – policies such as protectionism and occupational-licensing restrictions – are instead socially enlightened and “Progressive” policies that benefit the general public at the expense of business interests.