Years ago, when I was fresh out of school, I managed to get my foot in the door at Mass General Hospital, which I hoped would lead to a long career in medicine. I was hired to order supplies for a research lab but fancied myself a surgeon and had a way with self-promotion, and before I knew what was going on I was handed a hammer and chisel and invited into the operating room.
You can't imagine the things you see in people's brains when you're doing surgery on them! Honestly, people put tons of stuff up there and then totally forget that they did. Sometimes writers use the metaphor of an attic in an old house to illustrate the middle-aged brain, and it turns out to be a lot closer to reality than you might think. Lots of stuff sits in the corners of people's brains for decades completely undisturbed, swathed in cobwebs and random furfur. Average Americans rarely bother to do an annual spring cleaning of their brains, so the gray matter just gets more and more packed with useless junk until there is barely any room for new stuff. I'm convinced this is the reason that dads in midlife repeat themselves over and over. They want to store away their mostly boring tale of trying to obtain a cotter pin at the hardware store to fix their grandkids' wagon, but with all the cranial drawers and boxes full to the point of bursting, the anecdote sits there in plain sight for weeks and months so that friends and family can't get away from it.
As you can imagine, mixed in with the detritus are a few gems that a less-principled surgeon might have made off with. Noteworthy are bits of wisdom passed down through the generations that some people never paid attention to. Also, passwords to bank accounts. As an ethical person, I leave this stuff right where I found it.
Anyway, I got tired of doing brain surgery after a while. It started to get depressing. I tried for a few years to coax people into letting me clean out their brains for them, the way ENT surgeons I know upsell deviated septum patients by suggesting that they get full-blown nose jobs, but the resistance was fierce. People don't like to part with old stuff, no matter how useless it might seem to you and me. Truth be told, my brain still contains keepsakes from my own childhood. Few of us want to throw away the little bit that we manage to retain of life with mom and dad.