Montessori schools have a birthday ritual. When the boys were little, I’d go to the school to watch. In the middle of a small table, there was a candle burning. That was the sun. The birthday child held a globe. That was the earth. The child carried the globe around the candle. That was one year. Then all the children would examine a photo of the child at age one. Then the birthday child carried the earth around the sun again--and all would look at a picture of him at age two. And so on.

The kid’s face lit up—not just with the excitement of the birthday—but boggled by the tangible experience of holding the earth, of their own life meshing with the vastness and simple elegance of the workings of the sky.

That’s what I am doing today. I am going to carry our globe around the candle. A long hike—I’ve got a lot of revolutions to celebrate.