I have many issues with this statement. First, I'm having trouble picturing how this looks, no matter how many times I go back to re-read it. Second, Hemingway's got it all backwards. You put your hand on your head, not the other way around. That's weird, Hemingway, weird. And finally, I'm not sure if the hand is doing the rocking or the head. I expect antecedent issues from a third grader, not a magical, mystical writer who blows people's head's off with his books.
Also, let it be known that Count Mippipopolous has the best name in the history of mankind.
It reminds me of one of these!