[Yes, yes, I was being dramatic. And, not necessarily. Knowing makes fixing so, so much easier. Sometimes you learn as you try to fix, but I prefer not to do that, easy to mess it up or take way longer than it ought to.]

[Like how?]

[Hmm...]

[Fixing a computer, but you barely know what it's supposed to actually do and have no idea how it does it. So you try things for an hour or two until something looks like it's about right, then show it to the person you're fixing it for. They complain that it's all wrong, you broke it. Well, what is it supposed to be doing? And you let him explain and think some more and then try more things to fix, and eventually it works to the guy's satisfaction. But if I already knew this computer, I know that probably the problem is this thingy, and if it's not then it could be that one, and I can undo any bad changes I make by doing that... Sorry. It's hard to explain simply.]

[Guess so.]

[Anyway, it's better to know more about what you're trying to fix than less.]