Everyone knows the ancient joke about the two exhausted kids walking through a sun-blasted and waterless land. Sunburned and still miles from their destination, they come upon an immense pile of animal manure blocking their path. The boys stop for a moment to consider the obstacle mounded before them – feculent, still miraculously (in my telling) steaming – before the younger boy jumps quickly into the pile and begins digging furiously. His wee hands are a blur. Appalled, the older boy shrieks...