John O'Malley has been writing Catholic history for more than fifty years, and he has an enviable reputation for the clarity of his thinking and writing, and for the breadth of his deeply informed interests. He began as a student of the turbulent period before the Protestant revolt (with still valuable work on Giles of Viterbo, the great reforming prior general of the Augustinians). Since then he has written about the papacy, about the Society of Jesus across its distinguished and often controversial history, and about General Councils, especially those at Trent (1546–63) and Vatican II (1962–5). Now he brings all his experience and lucidity of mind to bear on Vatican I (1869–70). And he came to write it just after publishing a collection of his occasional papers suggestively entitled Catholic History for Today's Church: How Our Past Illuminates Our Present (2015). Because these were originally written for engaged Catholic readers (many were first published in the Jesuit review America), he has long sought to show the ropes of sand that connect past and present. He is very good indeed at negotiating that tension between the integrity of particular pasts and the untarnished legacies of the past in our present. His Vatican I ‘illuminates our present’, and his story of the yearning of so many for ‘certainty of faith’ is a story which, in terms of mindsets, is a yearning still very much with us and which still divides us. And of course, at the heart of his story is a desperate search for unchangeable truths. His book subverts by its very method many of the claims made then and now for particular kinds of irreformable truth.

Fr O'Malley has immersed himself in the literature of the Council and the literature of all that led to the Council. His bibliography is impressive for its length, and even more for its linguistic range: he has mastered a huge literature in Latin and in four European languages. Since the literature in the English language is very much weaker than the literature in French, German or Italian, this becomes almost by default the new standard work for the Anglophone world. I need to say that there is a brilliant and more insightful 60-page chapter by Owen Chadwick in his History of the Popes 1823–1914 which is not so much displaced as richly supplemented. But O'Malley still offers a magnificently lucid and shrewd account and analysis.

Trent and Vatican II are, he says, Councils whose outcomes could not have been predicted. Vatican I is a Council with a very predictable outcome. For this reason he devotes almost two-thirds of the book to what preceded it: the political threats to the Papal States, the waves of assault on the church from modernisers, nationalists, rationalists, new science, libertarians, egalitarians; and the increasingly Canute-like responses from a pope initially chosen for his geniality and common sense, who had been lashing out against all the provocations, but ineffectually. The culmination of this crisis was the Syllabus of Errors of 1864, a list of eighty modern errors that were ‘repudiated, proscribed and condemned’, and which culminated in anathemising the statement ‘that the Roman Pontiff can reconcile himself and come to terms with progress, Liberalism and modern civilisation’. But then there were scandals, such as the kidnapping of a child of Jewish parents who had been baptised by his nanny and then taken to the Papal States, where the church courts would refuse any redress to the distraught parents. The pope had his own Fox News to spin all this, but the free press across Europe told it how it was. ‘Democracy dies in darkness’ is the motto of the Washington Post, but in the 1860s, the outer darkness is where Pius IX sought to dump democracy.

That said, the last two chapters on the Council itself are gripping. The outcome was, in a broad sense, predictable (although the invasion of Rome by nationalist forces brough about a premature end when much was still to be discussed). But the precise form and language of the decree on infallibility was certainly not predetermined. The minority who opposed it were divided about how and indeed why to oppose. Almost all accepted that there was infallibility in the church. How personal to the pope was that infallibility? The minority assumed for too long that they were too many to be ignored – they assumed the decree would not be forced through by majority but by a ‘moral unanimity’, with concessions to permit them to make it a united front. Something like a moral unanimity was in fact achieved by give-and-take in the only other document promulgated at the Council, the Dogmatic Constitution Dei Filius, on the relationship of faith and reason. But on infallibility the majority used procedural rules and packed committees to ram through almost all of what they believed to be true.

In telling this story, O'Malley is outstanding. He juggles a large cast of activists on all sides; he makes us feel the frustrations of the endless repetition of points in a side chapel with appalling acoustics. He explains how the proponents of infallibility were limited more than anything else by tunnel vision, by hermeneutic rigidity, completely unable to make sense of Wissenschaft, historical-critical method. If its greatest champions were converts, its greatest detractors were historians from the German School. Not for the first, or last, time, scholasticism confronted humanism and won. And Pius IX comes out of it all as a man made rigid not so much by arrogance as by fear. He strove to build a fortress that would keep the modern world at bay. But he felt there all too many people inside his fortress ready to open the gates or wave white flags. Plus ça change…