Jack Vance says

We've got  an occupational disease to fight -- progressive mental myopia. We sit in this office. We think we know what kind of show we want. We send out our staff to get it. We're signing the checks, so back it comes the way we asked for it. We look at it, hear it, smell it -- and pretty soon we believe it. Our version of the universe, full-blown from our own brains like Minerva stepping out of Zeus. We've got our own picture of what's going on. We ask for it, we get it. It builds up and up and finally we're like mice in a trap built from our own ideas. We cannibalize our own brains. There comes a time in a man's life when he wants to take stock, get a new perspective. In our case it means taking our preconceived ideas, looking at them, checking our illusions against reality.