In this brief volume, Hans Urs von Balthasar exemplifies a method of ecumenical discussion that eschews both polemic and compromise. While unabashedly highlighting the central importance of those “features distinguishing the mystery of the (‘Roman’) Catholic Church from the other Christian confessions,” he does not offer a point-by-point refutation of Protestant (and Orthodox) objections. Instead, he shows that distinctive Catholic practices and beliefs are organic extensions and unfoldings of the revelation of the Trinity in Christ. Far form being accretions or optional extras, Balthasar argues, the Catholic distinctives prove to be integral to the fullness of the Christian mystery subsisting undiminished in the Catholica.