We were on the subway, on our way back to the hotel on our last night of vacation. The train was crowded when a family of four joined us for the ride. Mom and daughter found a seat, but dad and his young son went to stand in the seam between cars. Every time the train went around a bend, the floor would bend and twist, tossing the young boy around, with a huge smile on his face. Instinctively, he reached out and grabbed onto his father, who steadied him.