On explaining stuff

Many years ago I had a job as a writer of technical manuals.
If a machine was novel or its working wasn't common knowledge, the manual usually had some kind of theory section in it that explained how the machine worked. The idea was that if you understood how a machine worked, then if you encountered one in a nonworking state, you might have some idea what was wrong with it.
Every once in a while, actually, fairly often, I would get stuck writing these theory sections. What I was writing just didn't sound good. Invariably, after getting up from my desk and walking over to the coffee machine and thinking about the problem, I would discover that the source of my ineffective prose was a lack of understanding of how the machine worked. I was trying to explain something that I didn't understand. I discovered that if I didn't understand something, I couldn't explain it. I further discovered that this rule was pretty much true of anyone who sets out to explain something.
So the next time you read an explanation that doesn't make sense, chances are the person explaining it doesn't understand how it works. Read my next post on stability of small boats for an example of a topic that hardly anyone understands but many people feel compelled to write about all the same.
The other possibility, especially in journalism, when explanations don't make sense, chances are, somebody is lying.