I was once told that the human brain works in the background... and the proof to that was that sometimes you would be thinking of someone's name and not remembering, then stop thinking about it, and later on you'd remember, with no particular reason!
The question is: how does this work, and how long can the brain keep up with this stuff?
A couple of years ago I was given a problem I didn't solve by then... amazingly, yesterday morning, while still in bed, the answer simply ocurred to me
You have two doors, the right one and the wrong one. Your objective is to discover which is the right door. Outside the doors there are two lions. One of the lions always tells the truth, while the other always lies. You are allowed just one question, to one of the lions, without ever knowing whether he's the one telling the truth or not. What will your question be?
I'll leave you with the problem for a while