Things such as motorcycle maintenance manuals. Oh, not just those - physics equations, java programs, math problems too. Notice a trend here?
For some reason, I start panicking a bit while trying to figure out How Stuff Works, or to solve certain types of problems (Such as maths, physics and programming languages). So why do I do it? I guess there's a certain fascination in trying to push your limits.
You see, it isn't the easy stuff, it's those thoughts that I almost understand. Almost, but not quite. And trying to bend my mind around this new idea is frightening. It's like when I tried to grasp the concept of eternity and the void of space when I was a child and ended up having nightmares. It just wouldn't stop.
I feel like I have to somehow build a model of the concept in my mind. With usual things like fiction books this is easy; after all, there aren't that many original plots in existence. Philosophy is harder. But so are java programs.
The concept of void stopped frightening me after I grew up and understood that I could not understand it. Accepted that there are some things that a common human brain is not equipped to handle (but I won't vouch for Stephen Hawking).
The problem is, however, that my brain refuses to accept that I can't run a computer program in my mind, or to create an animated model of a bike's gearbox in my imagination. There must be people who can do that; after all, somebody wrote the program and invented the gearbox. And when my stubborn, stupid one-track mind can't accept that yes, there are things beyond my imagination, it goes into panic.
One of these days, I'll learn. Before that, though, there's this description of the inner workings of a carburettor that I've been meaning to check out.
Remember: slow, even breaths.
Motorcycle Carburetor Theory 101