Shortly after World War I, Romano Guardini formulated a sentence that soon became a standard quotation in German Catholicism: "An event of incalculable importance has begun: the Church is awakening in people's souls." The Second Vatican Council was the fruit of this awakening. It put into words and dedicated to the entire Church what had matured in the way of a knowledge born of faith in the four decades between 1920 and 1960 which were so full of beginning and hope. In order to understand the Second Vatican Council, we must take a look at this period and try to recognize, at least in broad strokes, the lines and currents that led to the Council. I want to begin in each case with the notions that were held during this period in order to develop from them the basic elements of conciliar doctrine in the Church.