One lesson that's very hard to learn, to really learn, is the one about not listening to cretins. Everybody brings a unique set of experiences, values, and biases to any conversation or exchange or judgment, and not only that, some of them are the experiences, values, and biases of cretins. By cretins I mean idiots, jackasses, gasbags, morons, fools, nitwits, and retards. Everybody is affected by the words of everyone else at all times and in all situations, no matter what they say. If I approached a renowned person, a towering figure in the arts for instance, and called his work bad and overrated and dreadful, to his face, he'd be affected by it, however briefly, despite his legions of slavering fans and admirers. No one's immune. Because he's renowned and his work bestowed with honors and encomiums, he is armored against the harsher effects of my words. His armor of lavish praise from every quarter, national and international recognition, awards to fill walls and mantles, none of it protects him from that initial sting, rather it softens the reverberations of my words through his skull, his armor is internal, it pads his emotional interior like the soft walls of a psychotic's white cell, preventing the hurt from lasting too long.

So it's foolish to tell someone, Oh don't listen to that idiot, he's crazy. Of course you'll listen, and of course for at least a brief moment you'll be absolutely convinced that what the cretin says is 100% correct, on the money. Then if you're lucky you'll be able to put it out of your mind.

Another complication to watch out for is that many people who say things like, Oh don't let such cretins bother you, are in fact cretins themselves, or at least somewhat foolish or wrongheaded individuals whose judgment you already know not to trust in many situations. It's like when you see a car with one of those "Don't Let The Bastards Get U Down" bumper stickers, and you pull up alongside it at a traffic light and glance over, and every time the driver looks like such a fucking bastard. But that's another problem entirely.