"The true makes of history are the spiritual men whom the world knew not, the unregarded agents of the creative action of the Spirit. The supreme instance of this-the key to the Christian understanding of history-is to be found in the Incarnation- the presence of the maker of the world in the world unknown to the world. ... The Incarnation is itself in a sense the divine fruit of history-of the fullness of time-and it finds its extension and completion in the historic life of the Church."