These illustrations and explanations read a lot like an attempt to explain how to swim to someone on dry land.

Histrionics rearing its head again.

I actually wasn't aware of the psychological associations with "histrionics." Being a nerd who watches commentaries for animated films, histrionics is often a term used to describe an animator's bad habit of constantly making the model move. You'll see this a lot in traditionally animated films, where motions are exaggerated -- it's typically done because our eye reads a non-moving animated character as flat and lifeless. I know gestures were a key part of classical rhetoric, so is this what Hume is advocating for here, an increased focus on the rhetoric of physicality?