When I was a small child I lived in Tehran, Iran, where I attended an international school. United Nations day was a day for carnival games and treats. We all dressed up to represent some part of our mixed heritage — because no one was all one thing or another – and we had a wonderful time. This Sunday we will look at the optimism that founded the UN and the fear that threatens it. How does the presence of cooperation among the nations affect the way we live and move in the world?