Come in, or the fog will get into the house.

[fflo]

That's a line in Dorian Gray--- the movie and the novel.  Is, or was, there an expression like that, or some superstition, or concern about the fog that way?  I couldn't find out with a little googling.  But it's a good line, isn't it?  A poem should start with it.

How would your poem go, if it started with that line?

I'll write one if you will.  We could all write one.  Just off-the-cuff, even.  Or not.