Rocking Rock

Back in the late last century my English friend lived in a first floor duplex on 4th Avenue and 12th Street. The main door was on the avenue, however the side door exited onto the street. It was kind of an alcove and homeless slept there and used it as a urinal. To stop this practice he hauled a huge rock down from the country. About the same size as the rocking rock and placed it in such a position to successfully stop the squatting. Happy story. Yes, but not for long. A week later he opened the back door and discovered that the rock was gone. Vanished. No trace of it. End of story. No. Two weeks later the rock returned to the alcove. I. The same same position, as if it had rematerialized from another dimension. We often speculated on the possibilities without arriving at a satisfying answer. A rock. A rock isn't. A rock is.