If we were a culture of high-risk alcoholics, and suddenly we had Jack Daniels piped into our houses, we would be feeding that fire. Social networking, and the internet as a whole, seems to have simply landed in an extremely fertile place in an extremely fertile time in history, when we all have these narcissistic tendencies anyway - you can go further back into the self-esteem movement, and Dr. Spock, and the 'everybody gets a ribbon at the track meet' sort of thing, which preceded the internet - and then you drop the internet into the middle of this, and we've all gone haywire.

The vexing thing about human behavior is that when we say we know we should do something, we really and truly do know it. It's hard to be 50 lbs. overweight or smoke a pack a day or feel miserable every moment you spend at work and not understand in a deep and primal way that change is in order - and that in some cases it could even save your life.

It's not mere extremism that makes folks at the fringes so troubling; it's extremism wedded to false beliefs. Humans have long been dupes, easily gulled by rumors and flat-out lies.

Narcissism falls along the axis of what psychologists call personality disorders, one of a group that includes antisocial, dependent, histrionic, avoidant and borderline personalities. But by most measures, narcissism is one of the worst, if only because the narcissists themselves are so clueless.

When we're awake, cortisol can fragment memories - one reason eyewitness crime scene accounts are so unreliable. But at night that very fragmentation allows creative recombinations of ideas.

There are a lot of ways to make people not like you, but one of the most powerful - if least fair - is to be really, really successful. Nobody resents the guy who just lost his job. But the guy whose Internet start-up made him a billionaire at 25? That's a whole different kettle of envy.

Indeed, the best way to think of willpower is not as some shapeless behavioral trait but as a sort of psychic muscle, one that can atrophy or grow stronger depending on how it's used.