"A democracy will continue to exist up until the time that voters discover they can vote themselves generous gifts from the public treasury."
That's why we're supposed to have a Republic, rather than a Democracy. Still, the cyclical nature of things, as you pointed out, is accurate.
A good book about this cyclical phenomenon is The Fourth Turning. (The same authors wrote Generations.)
Here's the editorial review of The Fourth Turning from the Library Journal (found at the Amazon link) --
After researching historical patterns, the authors (Generations: The History of America's Future, Morrow, 1991) conclude that America is on the verge of crisis. They substantiate their hypothesis by identifying and tracing a repetitive, four-stage historical cycle that, throughout recorded time, started on a high note and ended in hardship. Narrator Michael Tilford's polished, convincing voice and steady pacing lend an air of legitimacy to the authors' assertions. A brief question-and-answer session between the narrator and the authors at program's end provides an interactive quality that enhances the sometimes methodical drone of the historical analysis. Like other works of prophecy, The Fourth Turning should circulate well in public libraries.?Mark P. Tierney, The World Bank, Washington, D.C.
If I recall correctly, The Fourth Turning argues that there are mini-cycles of about 40 years each within grander cycles.