I was out shooting with a 4x5 view camera in a rocky, hilly area of a state park. For those who don't know, you focus a view camera on a ground glass sheet on the back of the camera with a black cloth over your head and the camera so that you can see the dim projected image. You also use a hand-held magnifier (a loupe) so that you can see the fine focus as you make adjustments.
Anyway, I had set the loupe on a nearby boulder, and somehow, it was knocked off (I can be a klutz). It was nowhere to be seen, and without it, I could forget about focusing critically, which is the whole point of lugging around the heavy view camera. It was then that I was struck by a stroke of genius. I found a small rock about the same size and shape as the loupe. I put it on the boulder and then knocked it off. I watched as it bounced and bounded downhill, finally coming to rest right next to the loupe, which had ended its own journey under the edge of a rock. I never would have found it without my little stroke of cleverness, which really saved the day.