Here's Bernard Mandeville's commentary on his Fable of the Bees (which provided an allegorical account of how the side effects of private "vices" (read "consumption" or "aggregate demand") are a public good) courtesy of JM Keynes (General Theory, Chapter 23, VII)
As this prudent economy, which some people call Saving, is in private families the most certain method to increase an estate, so some imagine that, whether a country be barren or fruitful, the same method if generally pursued (which they think practicable) will have the same effect upon a whole nation, and that, for example, the English might be much richer than they are, if they would be as frugal as some of their neighbours. This, I think, is an error.
The great art to make a nation happy, and what we call flourishing, consists in giving everybody an opportunity of being employed; which to compass, let a Government’s first care be to promote as great a variety of Manufactures, Arts and Handicrafts as human wit can invent; and the second to encourage Agriculture and Fishery in all their branches, that the whole Earth may be forced to exert itself as well as Man. It is from this Policy and not from the trifling regulations of Lavishness and Frugality that the greatness and felicity of Nations must be expected; for let the value of Gold and Silver rise or fall, the enjoyment of all Societies will ever depend upon the Fruits of the Earth and the Labour of the People; both which joined together are a more certain, a more inexhaustible and a more real Treasure than the Gold of Brazil or the Silver of Potosi.
And here's Keynes comment:
No wonder that such wicked sentiments called down the opprobrium of two centuries of moralists and economists who felt much more virtuous in possession of their austere doctrine that no sound remedy was discoverable except in the utmost of thrift and economy both by the individual and by the state. Petty’s “entertainments, magnificent shews, triumphal arches, etc.” gave place to the penny-wisdom of Gladstonian finance and to a state system which “could not afford” hospitals, open spaces, noble buildings, even the preservation of its ancient monuments, far less the splendours of music and the drama, all of which were consigned to the private charity or magnanimity of improvident individuals.
Apparently we are doomed to repeat history, except this time the Wall Street "knaves" get to shop and party while the rest of us get to be prudent, austere and (presumably) moral all the way to the soup kitchen. I'm sure they'll figure out a way for us to pick up their tab when they run the economy into the ditch again, too.
And you thought economics wasn't a morality play....