eureka eureka:
I don't think that democracy is "natural" in the sense that it is in any way innate. Virtually all advanced societies and Empires in the past have been built on slavery and autocracy.
However, the only societies that survive as advanced societies are progressive democratic ones. Democracy is a learned behaviour and a survival mechanism. Survival for the group. not the individual.
At first I was inclined to agree with you, mostly because of statements like Churchill's, but then I started to think about exceptions.
Take China for example. Its political evolution over the last 100 years or so has not followed what the western world would call democracy. A socialistic dictatorship at best. Yet it has survived and will continue to survive for the foreseeable future. Not all citizens are happy with the current structure and many in private will cautiously make statements about desired change. They also state how much better it is than it was 20 years ago. If advanced society means material goods and supporting infrastructure then China would be considered advanced.
So net, net I would have to say your statement is too broad.
Perhaps a better statement on democracy would be that it is a means to a desired state that satisfies the most needs. By that I would include not only material goods, but freedom of choice in most aspect of an individuals life.
I can accept the learned behaviour part of your statement just not 'the only societies that survive' part.