“Spring must not be permitted to arrive without notice”—to echo what I said in 2013. Every year this day gives me occasion to try understand again why our tilted axis causes the lengthening and shortening of days—and the two midpoints of this recurring cycle produce equal nights and days. On this day also, without fail, I wonder how, under current theories of planetary formation, we explain why our axial tilt exists at all. We watched a good documentary yesterday on Nova titled “The Incredible Journey of the Butterflies,” read Monarchs. Their navigational abilities are still not understood and never may be. Two great puzzles in succeeding days. What bumped the earth in some long night millions of years ago to make it tilt in its rotation?