John W. O'Malley is no stranger to readers of this Journal. Considered one of the great church historians of our age, his numerous publications, on both the history of the Jesuits and of church councils since the sixteenth century, have been translated into many languages and remain hugely influential. In 2019 he published Vatican I: the Council and the making of the Ultramontane Church; this brought to completion a trilogy of works that had begun with What happened at Vatican II (Cambridge, Ma 2008) and was followed by Trent: what happened at the Council? (Cambridge, Ma 2012). The present volume, beautifully designed and pocket-sized, almost as if it was deliberately intended as a vade mecum, might be understood as a distillation of the richness of O'Malley's trilogy, but with its own particular purpose. In laying side-by-side the deliberations of all three councils on which O'Malley has previously published, he offers, as it were, a synoptic solution to a problem that few scholars have heretofore cared to consider. The ‘problem’, of course, is not so much a puzzle to be solved, but a perspective to be adopted. In his introduction, O'Malley has no hesitation in stating that the content is wholly based on his previous books. However, the very decision to consider the three councils together yields new insights not only into the councils themselves, but conciliar history more generally.

The work is divided into three sections. The first considers three broad questions over three chapters, namely ‘What do councils do?’, ‘Does church teaching change?’ and ‘Who is in charge?’ The second section (consisting of four chapters) considers the participants at each of the councils: popes and curia, theologians, laity and ‘the other’. This is the most substantial of the sections. The third section (in two chapters) looks both to the past and the present, and also to the future, asking ‘What difference did the councils make?’ and ‘Will there be another one?’

Location, location, O'Malley reminds us as we begin. We may have got used to councils held at the Vatican by now, but this was quite the novelty in 1870. Earlier councils that had met in Rome had done so at St John Lateran. Trent, meanwhile, for historical reasons was the unlikely location for the major ecumenical council of the sixteenth century, concerned as it was to balance the wishes of Pope Paul iii and the Holy Roman Emperor Charles v. When compared with their roles at Vatican I and II, cardinals played little part at Trent, whereas cardinal legates did. At Vatican I it was the curia, with its now developed departmental structure, and on its home turf, which effectively ruled the roost. By Vatican II, the controlling positions enjoyed by the curial cardinals were much resented. In considering who was in charge at Trent and Vatican I, O'Malley remarks that the former was bishop-centred whereas the latter was pope-centred.

In reviewing the contributions of theologians to the three councils, O'Malley takes an excursion back to the emergence of the ‘schoolmen’ in the Middle Ages and what he describes as the bifurcation of teaching roles, the bishops claiming their right to teach as successors to the Apostles and the theologians by virtue of their professional training. This bifurcation ‘sometimes resulted in fruitful collaboration but at other times in resentment and rivalry’ (p. 106). He seems to relish relating that at Trent, for a time, bishops and theologians were placed together on deputations concerning doctrinal issues, a development that often exposed a bishop's theological inadequacies and was generally considered by their lordships to be odiosissimum (p. 110). As ever, O'Malley has an eye for the delightful detail such as that when the council transferred to Bologna in 1547 on account of plague, the mendicant studia, with their substantial libraries, served as an important resource for its work. International theological students based at the mendicant studia in Bologna were admitted to listen to the Congregation of Theologians until this had to be discontinued because of the swelling numbers. O'Malley points to the increased suspicion of universities at Vatican I, something that was not in evidence at Trent. The German Jesuit, Johann Baptist Franzelin, principal author of Dei filius, viewed the decree as directed at the semi-rationalists in the universities. But by Vatican II, one could find two theologians, and council periti, Karl Rahner and Josef Ratzinger, compose and circulate their own alternative to Cardinal Ottaviani's De fontibus among the attending bishops, something that would have been inconceivable at either Vatican I or Trent. O'Malley regards the development as follows: ‘at Trent and at Vatican I theologians ultimately served an existing theological paradigm whereas at Vatican II they gently overthrew it’ (p. 125).

Treating of lay contributions to the three church councils, O'Malley begins by considering the influence of emperors and monarchs on Trent, not least through bishops who were either directly or indirectly chosen by secular rulers. Theologians, too, often represented monarchs – Mary, queen of Hungary, sent no less than eight to Trent whereas the pope only sent two (p. 131). By Vatican I the situation had completely transformed; there were no invitations sent out to heads of state and this council became the first ecumenical council in history to have been shorn of direct lay participation. None the less, this did not mean that lay influence was completely absent. In many respects the movement of ultramontanism, itself a grassroots development, reached its apogee with the declaration on papal infallibility. By the time of Vatican II, no one seems to have even thought of inviting any heads of state to participate, O'Malley notes; however, this was not the case for the laity more generally. The first half of the twentieth century had seen an explosion in lay associations and organisations, not least the phenomenon of Catholic Action. On 8 October 1964 a draft document ‘On the lay apostolate’ was presented to the council, having been worked on by a number of laymen and women. At this stage Pope Paul vi had invited a number of lay auditors to attend the council. O'Malley might have mentioned one in particular, the Irishman, Frank Duff, founder of the Legion of Mary, one of the largest Catholic lay associations in the world.

In chapter vii, which deals with the relations of councils with ‘The other’, O'Malley identifies the sixteenth-century ‘Other’ as the Lutherans who were welcomed to the council for the first time in 1551, soon after which negotiations broke down. In the case of Vatican I, O'Malley doesn't see ‘The other’ as either Orthodox Christians or Protestants (both of whom were ‘reached out to’ by Pius ix, but not in any meaningful way that might have offered a constructive way forward); rather, ‘The other’ at Vatican I was liberalism, that catch-all term for rationalism, atheism, democracy, disrespect for authority and tradition, radical secularisation, etc. By Vatican II, O'Malley continues, the ‘modern world’ was not considered to be a reality separate from the Church. Christian Democracy leaders such as Adenauer, De Gasperi and Schuman were all Catholics who took for granted freedom of the press, freedom of religion and some form of separation of Church and State, positions that Pius ix's pontificate had railed against (p. 165). Meanwhile, Nostra aetate ‘gave Catholics a new job description. They were now to be agents of reconciliation among the religions of the world’ (p. 198).

There is much to praise in O'Malley's new book. It will serve as refresher course for many on aspects of all three councils and will cause readers to look at them collectively in new ways. That said, it's no substitute for reading O'Malley's own longer treatments of all three councils, which remain indispensable resources for those who wish to fully appreciate the complexities of the councils and the issues that they dealt with.