“There must therefore be a considerable class of persons who have both the will and power to consume more material wealth then they produce, or the mercantile classes could not continue profitably to produce so much more than they consume.”

Source: The Wealth of Nations (1776), Book IV, Chapter VIII, p. 721.

also reported in the form: The peoples of the Balkans produce more history than they can consume, and the weight of their past lies oppressively on their present.
Although widely attributed to Winston Churchill (e.g. by the President of the British Academy, Professor Sir Adam Roberts), the quote is spurious.
The remark was quoted - although without attribution, and concerning East Central Europe instead - by Margaret Thatcher in her speech, "New Threats for Old," in Westminster College, Fulton, Mo., at a joint commemoration with the Churchill Centre of the "Iron Curtain" speech's 50th anniversary, on 9 March 1996: "It is, of course, often the case in foreign affairs that statesmen are dealing with problems for which there is no ready solution. They must manage them as best they can. That might be true of nuclear proliferation, but no such excuses can be made for the European Union's activities at the end of the Cold War. It faced a task so obvious and achievable as to count as an almost explicit duty laid down by History: namely, the speedy incorporation of the new Central European democracies--Poland, Hungary and what was then Czechoslovakia--within the EU's economic and political structures. Early entry into Europe was the wish of the new democracies; it would help to stabilize them politically and smooth their transition to market economies; and it would ratify the post-Cold War settlement in Europe. Given the stormy past of that region--the inhabitants are said to produce more history than they can consume locally--everyone should have wished to see it settled economically."
The sources of Thatcher's quote is likely a passage in the 1911 "Chronicles of Clovis", by Hector Hugh Munro (Saki), referring actually to Crete: "It was during the debate on the Foreign Office vote that Stringham made his great remark that "the people of Crete unfortunately make more history than they can consume locally." It was not brilliant, but it came in the middle of a dull speech, and the House was quite pleased with it. Old gentlemen with bad memories said it reminded them of Disraeli."
Misattributed
Source: Reinventing the Wheel http://www.gresham.ac.uk/lectures-and-events/reinventing-the-wheel-the-cost-of-neglecting-international-history. Footnote #5
Source: The speech is in James W. Muller, ed., Winston Churchill's "Iron Curtain" Speech Fifty Years Later (Columbia: University of Missouri Press, 1999), which collects the papers from that occasion. A readable .pdf is on the Churchill Centre website (scroll to pages 18-24): http://www.winstonchurchill.org/images/finesthour/Vol.01%20No.90.pdf
Source: Full text available here: https://en.wikisource.org/wiki/The_Chronicles_of_Clovis/The_Jesting_of_Arlington_Stringham

As quoted in Quote Unquote (A Handbook of Quotations) (2005) by M. P. Singh, p. 86

p 10.
Pornography, Men Possessing Women (1979)

Book II, Chapter I, On The Progress of Wealth, Section IX, p. 410
Principles of Political Economy (Second Edition 1836)

Source: Globalization - A Basic Text (2010), Chapter 10, High-Tech Global Flows and Structures, p. 290

Source: A Treatise On Political Economy (Fourth Edition) (1832), Book I, On Production, Chapter XXI, Section V, p. 238
Context: And let no government imagine, that, to strip them of the power of defrauding their subjects, is to deprive them of a valuable privilege. A system of swindling can never be long lived, and must infallibly in the end produce much more loss than profit.

Principles of Communism (1847)

The portion of this statement, "Love is the only sane and satisfactory answer to the problem of human existence" has been widely quoted alone, resulting in a less reserved expression, and sometimes the portion following it has been as well: "Any society which excludes, relatively, the development of love, must in the long run perish of its own contradiction with the basic necessities of human nature."
The Art of Loving (1956)
Context: Our society is run by a managerial bureaucracy, by professional politicians; people are motivated by mass suggestion, their aim is producing more and consuming more, as purposes in themselves. All activities are subordinated to economic goals, means have become ends; man is an automaton — well fed, well clad, but without any ultimate concern for that which is his peculiarly human quality and function. If man is to be able to love, he must be put in his supreme place. The economic machine must serve him, rather than he serve it. He must be enabled to share experience, to share work, rather than, at best, share in profits. Society must be organized in such a way that man's social, loving nature is not separated from his social existence, but becomes one with it. If it is true, as I have tried to show, that love is the only sane and satisfactory answer to the problem of human existence, then any society which excludes, relatively, the development of love, must in the long run perish of its own contradiction with the basic necessities of human nature. <!-- p. 111 - 112