I sometimes think about the fact that my children (assuming they will be born when I'm in my thirties) will be as far removed chronologically from the Beatles, Pink Floyd, Led Zeppelin, the Doors, etc. (i.e. the music I listen to most often) as I am from music of the 1930s, of which I hardly know any.
There's a lot of background mess in our mental pictures of the world. We try and be accurate on important issues, but a whole lot of the less important stuff we pick up from the media, the movies, and random impressions. And once these impressions are in our mental pictures, they just don't go away - until we find a fact that causes us to say "huh", and reassess.
Here are three facts that have caused that "huh" in me, recently, and completely rearranged minor parts of my mental map. I'm sharing them here, because that experience is a valuable one.