Vidal has been throwing around this quotation by Benjamin Franklin, made during a speech at the conclusion of the Constitutional Convention, September 17, 1787:

In these moments, Sir, I agree to this Constitution, with all its faults, -- if they are such; because I think a general Government necessary for us, and there is no form of government but what may be a blessing to the people, if well administered; and I believe, farther, that this is likely to be well administered for a course of years, and can only end in despotism, as other forms have done before it, when the people shall become so corrupted as to need despotic government, being incapable of any other.