His mouth started to speak, but his brain decided it hadn't got anything to say yet and shut it again. His brain then started to contend with the problem of what his eyes told it they were looking at, but in doing so relinquished control of the mouth which promptly fell open again. Once more gathering up the jaw, his brain lost control of his left hand which then wandered around in an aimless fashion. For a second or so the brain tried to catch the left hand without letting go of the mouth and simultaneously tried to think about what was buried in the ice, which is probably why the legs went and Arthur dropped restfully to the ground.