Recently someone told me that there is an island on a lake in an island on a lake in an island in Canada. I can’t quite picture this; the triple island remains foggy in my mind’s eye, surrounded by five (or are there six?) receding concentric shores. If I imagine it in reverse — in Canada there is an island with a lake that contains an island with a lake that contains an island — the arrangement is slightly more stable. The picture’s resolution increases dramatically, however, if I attach artificial details to the triple island construction. For example, I have no trouble picturing a turtle sunning itself on a rock in the middle of a rain puddle on Turtle Island on Turtle Pond in Central Park, Manhattan, despite the fact that the configu­ration is identical to the unnamed Canadian island.