Drawing on history, Scripture, and ideas proffered by great thinkers of the past, and with an emphasis on the need for unity, responsibility, and faith, Obama's speeches look to the future, to a destiny that will "not be written for us, but by us." Here are the words that made us stand still when we heard them, awed by their grace and power, the words that were at the same time a rousing call to action, galvanizing millions to embrace a new world and face its daunting challenges.