(In which my dislike of blog posts consisting of pointed quotations is overcome by my love of Douglas Adams.)
"I think," said Ford in a tone of voice which Arthur by now recognized as one which presaged something utterly unintelligible, "that there's an SEP over there." . . . .
Arthur experienced that dull throbbing sensation just behind the temples which was a hallmark of so many of his conversations with Ford. His brain lurked like a frightened puppy in its kennel. Ford took him by the arm.
"An SEP," he said, "is something that we can't see, or don't see, or our brain doesn't let us see, because we think that it's somebody else's problem. That's what SEP means. Somebody Else's Problem. The brain just edits it out, it's like a blind spot. If you look at it directly you won't see it unless you know precisely what it is. Your only hope is to catch it by surprise out of the corner of your eye."
"Ah," said Arthur, "then that's why ..."
"Yes," said Ford, who knew what Arthur was going to say.
"... you've been jumping up and ..."
"... down, and blinking ..."
"Yes." . . . .
The ultra-famous sciento-magician Effrafax of Wug once bet his life that, given a year, he could render the great megamountain Magramal entirely invisible.
Having spent most of the year jiggling around with immense Lux-O-Valves and Refracto-Nullifiers and Spectrum-Bypass-O-Matics, he realized, with nine hours to go, that he wasn't going to make it.
So, he and his friends, and his friends' friends, and his friends' friends' friends, and his friends' friends' friends' friends, and some rather less good friends of theirs who happened to own a major stellar trucking company, put in what now is widely recognized as being the hardest night's work in history, and, sure enough, on the following day, Magramal was no longer visible. Effrafax lost his bet - and therefore his life - simply because some pedantic adjudicating official noticed (a) that when walking around the area that Magramal ought to be he didn't trip over or break his nose on anything, and (b) a suspicious-looking extra moon.
The Somebody Else's Problem field is much simpler and more effective, and what's more can be run for over a hundred years on a single torch battery. This is because it relies on people's natural disposition not to see anything they don't want to, weren't expecting, or can't explain. If Effrafax had painted the mountain pink and erected a cheap and simple Somebody Else's Problem field on it, then people would have walked past the mountain, round it, even over it, and simply never have noticed that the thing was there.
- Douglas Adams, Life, the Universe, and Everything