In the great opening verses of the Sermon on the Mount, Jesus lays out, in short order, his ethical and spiritual program. It turns all of our customary expectations and prejudices upside down. To be "happy," fulfilled, we must empty the self, become meek, learn how to sorrow, hunger not for egotistic satisfaction but for justice, work for peace, and become the objects of persecution. Strange, puzzling, unnerving, counter-intuitive--and the key to joy.