Yesterday was our montly book sale. Calvin and Jon came to help first thing in the morning, but with Calvin finding a new book to take home every ten minutes, I'm not sure how much help that really was. Between finding books, though, he had a long conversation with the board president about penguins, the difference between the northern and southern hemispheres, the human migration to the Americas, and finally the Mayas. When I got home from the sale (after Jon and Calvin came back to help close the sale and clean up) Calvin and Jon had been, in addition to straightening and shopping, building a Mayan city. They finished it today. A temple, a ball court, farm lands, and even sacrificial altars, the city is now complete. Calvin alternates beween playing "classical era," when the city is inhabited and lively, and "modern era," when the city is being excavated. It's pretty awesome.