How to judge politicians: Polybius

Use the adversity test:

“In everyday life, if people intend to reach a true assessment of someone, to decide whether he is bad or good, they do not base the investigation on those periods of his life when he was untroubled by external circumstances; they look at how he behaved when he was afflicted by misfortune or blessed by success, because they think that the only way to tell whether a man is fully qualified is to see whether or not he is capable of enduring total changes of fortune with courage and without compromising his principles. This is how one should examine a system of government as well.” (Polybius, Greek hostage to Roman conquerors, later friend of Scipio Africanus the Younger, and author of many historical works)

More at my Quotations page.