On etymological opacity as a force for linguistic change.

I've been thinking about how languages develop recently. It beats thinking about work.

Now, I know that this is all stuff that any half-trained historical linguist will look at and go ‘duh!’, but I'm not even half-trained. This is all stuff I've picked up, and figured out, and this is just trying to put them into some sort of order, so as to make sense of them.

( Feel free to ignore this if you're not a linguaphile )