>>>BTW, I was just looking at your web site, and I can't find any explanation there as to why 'Slow up' and 'Slow down' mean the same thing.
>>
>>Is there such an explanation?
>
>I was hoping that you, as guardian of the language arcana, would know.

They (the anglophone population) must have sneaked (snuck?) that while I was sleeping.

Language doesn't really have to make sense, it just should, if it feels like.

Take climbing, for instance. You "climb the tree" - never saying whether it's up or down. Because "up" is the default. But there's no reverse verb, you have to "climb down". So ok, it's either up or down - and when you're done climbing up, where are you? You're "IN" the tree.

In Serbian, you can be in the tree only if it has a hollow trunk. And there's a verb for "climb down".

Conversely, when you get INTO a bus, where are you?