Professor von Aretin traces the history of papal involvement in temporal matters, from the imprisonment of Pius Vii by French troops early in the nineteenth century, Leo XII's communist contacts in the 1960's. He gives a wealth of detail on the background to Catholic movements in Europe and America as these functioned outside the Vatican itself . His conclusion is that the future of the papacy lies in grasping the potential for leadership that has for so long been at hand, but which,if let slip once more, will reduce Catholicism to an insignificant sect.