I like these from the De Rerum Natura (Concerning the Nature of Things) by the Roman poet and Epicurean Lucretius, a contemporary of Cicero and Julius Caesar (all quotes are from the Loeb edition):
1. Speaking of credibility: "Thus it is more useful to scrutinize a man in danger or peril, and to discern in adversity what manner of man he is: for only then are the words of truth drawn from the very heart, the mask is torn off, the reality remains" (Book 3.55-58);
2. Speaking of the frenetic search for entertainment: "[E]ach man tries to flee from himself" (Book 3.1068).
I think of No. 1 on credibility especially when we see people caught doing what is unethical and refusing to own up. I think of No. 2 on freneticism when we see so many erratic individuals with a lot of strong opinions, emotions, and judgments and no maturity.
(Image of the book De Rerum Natura in public domain)