If we ask ourselves why it should be that the Roman Catholic Church has been so vitally interested in the theology of an incorrigible twentieth-century Swiss Calvinist, Karl Barth, the answer is very likely to lie in the recovery which his theology made of the idea of divine authority in the Church. That he saw the implications of this recovery from a Protestant perspective is no more than one would expect. The passage which I have quoted from a lecture of 1928 is immediately followed by a reference to Luther and Calvin:

And it follows from this remark that if we ask ourselves why it has been possible in the last twenty years for the Roman Catholic Church to become so vitally interested in the theology of the two chief reformers of the sixteenth century, the answer is just as likely to lie in the impetus given by Karl Barth's theological career to recapture the sense of the divine indwelling in the Church which informs so much of their work.