In the present century a renaissance in Roman Catholic theology sparked a renewed interest in the theology of nature and grace. Without an understanding of the heated debate that raged in mid-century over the nature/grace dialectic, Vatican Council II is not wholly intelligible, for with this dispute Catholicism turned a corner. The theology of nature and grace that emerged from the debate furnished a theoretical foundation for exorcising the dualisms that for so long had bedeviled Catholic life and thought, and thus legitimated Catholicism's departure from its ghetto and its new openness to the world. The quotidian and the religious were now seen to reside not in separate enclaves, but to suffuse each other. The plain truth of the humdrum was transformed into poetry, and poetry into revelation. This historical and interpretative study chronicles the mid-century debate and analyzes the contributions of the major players and a cast of representative figures.