I tend to think of Nantucket as this place that is constantly shifting, and in many ways it is. People come and go, drift with the seasons and the tides. Our population ebbs and flows from some 17,000 in the off season to close to 50,000 in the summer. This time of year, school break arrives and the island clears out except for the few of us left behind to make sure the lights stay on and the dogs get walked. A hearty handful of businesses stay open, but the rest shutter their doors and take a much needed break. After all, the high season is already on the horizon.