Phantom scratching is like pain
A while ago I shared this picture of three-legged cat Isaac, trying to scratch himself with his missing leg:

Now a little to the left …. Photo by Reddit user ElenTheMellon.
It was poignant and interesting, but I wasn’t sure what to make of it for this here website. What’s the significance? What does it demonstrate about pain? It took me a couple weeks, but here’s what finally came to me in the shower this morning:
Pain works like this. The pathetic futility of Isaac’s scratching does not stop his brain from trying to scratch. The brain has a picture how things should be, and acts accordingly (or makes you act accordingly). The impulse is like a freight train, even when it’s blatantly ineffective. So it often goes with pain: if your brain believes there’s a threat, you’re going to hurt, no matter how pointless it is, no matter how intensely you focus on trying to have more reasonable and rational sensations.
This great little example is now included in Pain is Weird, to help explain that mind-over-pain hope is problematic.