$PI $PI Sir, look back—your small boat has already passed through ten thousand layers of mountains; look ahead—the road ahead is long, yet bright; look up—human life and its fires are dazzling and thriving; look down—more than half of the thorny road has already been crossed. You have to endure, until bitter turns to sweet; you have to wait, until spring is warm and flowers bloom. May there be a path under your feet and light in the distance. When you take your steps, may your grand blueprint be fully realized!