On the day that students and the people who love them marched in cities and towns around the world, my husband and I walked the wide boulevards of Chichén Itzá. If our trip to Mexico had not been planned so far in advance, we too would have been marching in our hometown. Instead, heat-dazed, we gazed at the ruins of the ancient city that has long been known as a site of copious human sacrifice.   The Mayans, and the Toltecs who conquered them, believed that the gods were hungry for blood, in particular the blood of fresh human hearts. When the divine appetite for blood was sated, the sun would rise and the crops would thrive. Legend has it that the gods preferred the hearts of young warriors. That only the hearts of the strongest, healthiest, most beautiful young people would please the gods’ delicate palates. Hundreds of years from now, will tourists visit the ruins of American schools and shake their heads in horror? Will they ask why we, a once-advanced civilization, were willing to sacrifice our young because we believed—what, exactly? That it was a sacred right to own the deadliest of weapons? At least the Mayans and the Toltecs thought they were making the sun rise.          As I write, Passover has begun and Easter is tomorrow. I’m back in Seattle now, but I started this holy week in Valladolid, Mexico, a quiet, colonial city near Chichén Itzá. On Palm Sunday, I attend 9 o’clock mass at the Templo de San Bernardino, [...]