He said, “Well, what would happen if a plane dropped you in the middle of the Sahara Desert and you picked up a single grain of sand with tweezers and moved it one millimeter?” I said, “I’d probable die of dehydration.” He said, “I just mean right then, when you moved that single grain of sand. What would that mean?” I said, “I dunno, what?” He said, “think about it.” I thought about it. “I guess I would have moved a grain of sand.” “Which would mean?” “Which would mean I moved a grain of sand?” “Which would mean you changed the Sahara.” “So?” “So? So the Sahara is a vast desert. And it has existed for million of years. And you changed it!” “That’s true!” I said, sitting up. “I changed the Sahara!”