This is beautiful and really fired me up. The closing 'graf of the Wriston Lecture at the Manhattan Institute.
A later realization—I suppose I have sensed it most of my life, but I have understood it philosophically only during the preparation of this talk—has been the beauty of the idea of the pursuit of happiness. Familiar words, easy to take for granted; easy to misconstrue. This idea of the pursuit of happiness is at the heart of the attractiveness of the civilization to so many outside it or on its periphery. I find it marvelous to contemplate to what an extent, after two centuries, and after the terrible history of the earlier part of this century, the idea has come to a kind of fruition. It is an elastic idea; it fits all men. It implies a certain kind of society, a certain kind of awakened spirit. I don't imagine my father's parents would have been able to understand the idea. So much is contained in it: the idea of the individual, responsibility, choice, the life of the intellect, the idea of vocation and perfectibility and achievement. It is an immense human idea. It cannot be reduced to a fixed system. It cannot generate fanaticism. But it is known to exist; and because of that, other more rigid systems in the end blow away.
(Hat tip: Andrew Sullivan)