"A democracy cannot exist as a permanent form of government. It can only exist until the voters discover that they can vote themselves largesse from the public treasury. From that moment on, the majority always votes for the candidates promising the most benefits from the public treasury with the result that a democracy always collapses over loose fiscal policy, always followed by a dictatorship. The average age of the world's greatest civilizations has been about 200 years. These nations have progressed through this sequence: From bondage to spiritual faith; From spiritual faith to great courage; From liberty to abundance; From abundance to selfishness; From selfishness to apathy; From apathy to dependence; From dependence back into bondage." - Alexander Fraser Tytler.
(h/t Daily Dish).
Update: Joe Sucher has informed me that the provenance of the above quote is in dispute. See the wikipedia article on the author for the details. Anyway, I thought it was a good quote.