It is the Gyges ring parable.
A man find a ring that makes him invisible (total privacy). And then he does steal, introduce himself in houses and watch women undress and rape them ... and then he becomes a bloody tyran.
The moral of the story is invisibility/privacy makes people bad because moral behaviour is a result of the look of the other on your actions.
Needless to say Plato was an asshole. So is conclusions was to create the Republic where the wise would be hidden from the masses, control the masses, censor them ...
Greek myths however said you could evade from the look of the other but not the one of your own conscience and that the chtonian gods (Eryhnies & al) would come and get you.
I think that people are mostly having a conscience, but that the lack of transparency favors the one having none (psychopaths) and that psychopaths are attracted to power like pedophile are attracted to teaching kids.
Thus, I am puzzled that knowing this we let the more powerful have the most privacy. Hence my fight for the transparency of the most powerful persons, the exact opposite of today's law. As a result, I think privacy is actually a bad thing.