John Kenneth Galbraith (1908-2006) has been credited with many, many quotable quotes. Here is one about conservatives:
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness.
Here is another about two Great Political Systems:
Under capitalism, man exploits man. Under communism, it's just the opposite.
And, finally, here is the Galbraith's Law of Resignation:
Anyone who says he won't resign four times, will.
Of course, you can read many, many more here.
The NYTimes obituary provides another interesting quote, this time from Amartya Sen:
Mr. Sen said the influence of "The Affluent Society," was so pervasive that its many piercing insights were taken for granted.
"It's like reading 'Hamlet' and deciding it's full of quotations," he said.