One annoying piece of advice from a know-it-all fictional character immediately after stating some dubious political opinion such as "whenever people turn to entertainment rather than to duty, the system collapses within a decade", or "democracies only last fifty years" is: "read the histories!" This is supposed to demonstrate the truth of the assertion.

Robert Heinlein, for example, liked to do this, and I think he got it from GB Shaw.  They never say which histories, exactly, though I suspect they mostly mean works by Thucydides, Tacitus, and Plutarch. A Classical historian writing about Classical events with a moralizing atttude always gives the most status to your pronouncements.

I read the histories. The more I read, the less sure I am that they really tell us anything particularly clear about what moral virtues we should possess to successfully run a civilization, or a life. The Romans were corrupt, depraved, and totally self-interested while they were on their way up, while they ruled a vast empire, and while they were on their way down. Trying to find some kind of overall civic virtue among the squabbling generalissimos of the Later Republic is a futile endeavor.  Republican government was then submerged in the rule of the Emperor--and the system went on from triumph to triumph for another two and a half centuries, and remained incredibly powerful for two centuries beyond that.  What does that tell us about republican virtue?

And then there are the events, and the interpretation of them. To have to clearly distinguish between what is known to have happened, and what people of said about them: "This is reminiscent of the way William III had to let James escape to the Continent so he wouldn't have to try him: Macauley's account is not without interest here...." or "You cite Justinian's reconquest of the West as an example of imperial overstretch, but there is reason to believe that without the plague, he might well have succeeded in reincorporating at least North Africa and Italy for the long term...and don't pay too much attention to Procopius, that Sixth Century Kitty Kelley."

Of course, once you get specific, you've given your opponent (or person you're trying earnestly to instruct) something to argue with: "Just think of how much better atheists would have handled both those situations!" Better to stick with "read the histories".