Out of World War I has come an apocryphal story about a young second lieutenant who had failed to get his stubborn army mule to move. He asked for help from his sergeant, a veteran mule trainer. The trainer picked up a plank of wood. Without changing his expression, he crashed it down on the mule’s head, right between his ears. The astonished officer remonstrated: “That’s no way to teach a mule!” The sergeant replied casually: “I haven’t started to teach him yet. That was just to get his attention!”

From James H. Austin’s Zen and the Brain, Cambridge, Massachusetts: The MIT Press, 1999 (first published in 1998), pp. 120-121.