First a practical example on how the mirror neuron system works:
http://www.youtube.com/watch?v=Iys86OcXPY8
Did you have to laugh? Why was it so funny? Not because of a joke bringing about the neuronal correlate of absurdity but because of your mirror neurons getting activated by watching somebody else's body, and getting activated as if you were having that experience yourself.
That makes me wonder how our society would be changed if TV and movies and internet would show only good and strenghtening experiences, that make you happy and joyful.
And makes me understand why somebody with a wonderful genetic predisposition can't feel fine with ugly people in the surrounding...
(Not that you couldn't stand a few ugly people - you can always blank them out -, but if you'd have to blank out everybody it won't work.)
And it makes me wonder what is more important to our well-being, to perceive nice people directly (or visually via some media, be it electronic or non-local), or to read their nice sentences on paper or on the computer screen. (Which, however, is preferable to not knowing that there are nice people in the world whatsoever.) (And which, at least, always spurs your thinking.)