New Years Day. the ritual of changing the calendars. I take down the old  Nature Conservancy calendar, with its beautiful wildlife pictures, and hang its replacement,  the 2010 calendar.  I replace the little tide book tucked behind the portable radio on a kitchen counter. My book shows the high and low tides as a wavy line undulating across the days of the month. My moon chart too is visual: for each month, an arching line of moons, their phases making a dramatic pattern of light and dark across the year. I love these graphic images. I love too, that by comparing the charts for moon and tide,  I can see the pull of the moon’s gravity on water, can glimpse the rhythms that make up our world.