Summa de potestate ecclesiastica.

First edition of this highly important and influential magnum opus of political theory, a defence of papal supremacy.

The author's principal work, completed in 1326, it runs to nearly half a million words and went through four further editions before 1501; it was repeatedly printed throughout the following century, with the last edition appearing in 1582. It was also the last (and most substantial) book printed by Schüssler, the Augsburg printer so admired by William Morris for his presswork, who later in 1473 sold his five presses to the Monastery of SS. Ulrich and Afra, also at Augsburg.

Augustinus had taught philosophy and theology at Paris (lecturing on Peter Lombard's Sentences) and Padua, before serving as chaplain to Charles, son of Robert, King of Naples. He engaged with the most crucial philosophical issues of his age, writing extensively on logic (including a commentary on Aristotle's Prior analytics), psychology, and metaphysics, as well as composing several theological treatises and biblical commentaries. The Summa on the authority of the Church was dedicated to Pope John XXII (whose court at Avignon was engaged in an enduring stand-off with the Holy Roman Emperor) and was completed by 1326, two years before Augustinus's death. It was a timely publication. Two years earlier Marsilius of Padua, with his Defensor pacis, had stated a wholly anti-papal theory: though also positing a single seat for supreme spiritual and temporal authority, he had placed it with 'the Christian people' rather than with the pope. Another, more complex, challenge to the supremacy of papal authority came at the same time from William of Ockham, who spectacularly became the first Western theologian to break with a reigning pope on matters of faith by pointedly leaving the Avignon curia and escalating his long-standing anti-papal dissent in 1328. Several of what would be Ockham's lines of attack (for example the possibility and mechanics of deposition of a pope who has fallen into heresy) are tackled early on in Augustinus's first quaestiones, showing an awareness of the urgency of such arguments, as well as displaying legal and theological heft in their handling. Particular openness and sensitivity are shown in quaestio 7, on the possibility of censure or correction of the pope: here Augustinus supports such censure, even in public, when it is done for the protection and welfare of church and society, to some extent anticipating, perhaps, conciliarist positions later adopted by Ockham and others.

Augustinus is the central figure in M.J. Wilks's The problem of sovereignty in the Later Middle Ages: the papal monarchy with Augustinus Triumphus and the publicists (Cambridge, 1963): 'The Summa de potestate ecclesiastica of Augustinus Triumphus has been described as one of the half dozen most influential and most important books ever written on the nature of the papal supremacy in the Middle Ages, and to disregard his work is to neglect and obscure some of the outstanding features of a crucial moment in the genesis of modern political ideas. Not only was Augustinus Triumphus a political thinker of the highest calibre, but it is also perhaps true to say that he alone amongst the publicists of the thirteenth and fourteenth centuries gives a really complete and adequate account of the maturer stages of papal-hierocratic doctrine' (p. 2).

The value of the effort to understand and define the relationship between church and state which underpins the work of Augustinus and his contemporaries did not remain confined to their time: their arguments went on to influence the theorists of the conciliar movement of the fifteenth century, the reformers of the next century, Althusius and Grotius, and in turn the early modern political thought of Hobbes and Montesquieu.

GW has distinguished no less than six variants of the printed slip tipped in at [q]3. Our copy has variant 5; the slip contains two lines of omitted text (printed over four lines). The binding stamps are unrecorded by Kyriss and Schwenke, but the Einbanddatenbank gives them to a workshop possibly based in Munich and active circa 1465–1475 (München Cgm 393 *).

Provenance: from the library of the Augustinian Hermits of Seemanshausen, Bavaria, with eighteenth-century ownership inscription on front pastedown 'Ad usum Fr. Angeli Ord. Erem. S. Augustini . . . iam ad Conventum Seemanshusanum'; from the library of Hans Furstenberg; formerly item 7 in Martin Breslauer Catalogue 106.

Hain 960; GW 3050; BMC II p. 329; Goff A-1363; IGI 1062; Bod-Inc. A-499; ISTC ia01363000.