Sort of a twofer:
I do not say that democracy has been more pernicious on the whole, and in the long run, than monarchy or aristocracy. Democracy has never been and never can be so durable as aristocracy or monarchy; but while it lasts, it is more bloody than either. … Remember, democracy never lasts long. It soon wastes, exhausts, and murders itself. There never was a democracy yet that did not commit suicide. It is in vain to say that democracy is less vain, less proud, less selfish, less ambitious, or less avaricious than aristocracy or monarchy. It is not true, in fact, and nowhere appears in history. Those passions are the same in all men, under all forms of simple government, and when unchecked, produce the same effects of fraud, violence, and cruelty. When clear prospects are opened before vanity, pride, avarice, or ambition, for their easy gratification, it is hard for the most considerate philosophers and the most conscientious moralists to resist the temptation. Individuals have conquered themselves. Nations and large bodies of men, never.The remedy, of course, was to form a Republic, and for over two hundred years the Republic endured. Now it is to be converted into a democracy, and the result is predictable and predicted. There are many good studies of what happens when a democracy commits suicide. If it is fortunate it gets a Claudius Caesar, but more often it must first endure a Caligula so that Claudius seems a blessed relief. And after Claudius as likely as not comes Nero. But I digress. For the moment we do not yet have Marius.[Highlighting by PF]
John Adams, letter to John Taylor (15 April 1814).