"Well," he says, thoroughly - how would Tahani put it? chuffed - that she wanted to learn from him, of all people, "you've got a decent start to it, but -" a friendly chortle that was meant to disarm just as much as her cuteness, "-you're also seriously really, really wrong. I mean - choice? That's not a dimension, it's a concept. Look, just ... treat your brain like an Etch-a-Sketch and shake your head around a bit."

He waited patiently for her to, you know, actually do it.