AILLY, PIERRE d’ (PETRUS DE ALLIACO). — Scientist, philosopher, theologian, confessor to Charles VI, statesman, bishop, and cardinal, he was one of the most illustrious figures in the Church of France during the 14th and 15th centuries, indeed in the entire Middle Ages. He was called the “Eagle of France” and also the “untiring hammer of those who stray from the truth.” Born in 1350, according to most sources in Compiègne, into a well-to-do but not noble family originally from Picardy, he died in Avignon on 9 August 1420 after making substantial donations to churches, the poor, hospitals, and the Collège de Navarre. His remains, transferred to Cambrai in 1422, rested in the tomb he had prepared within the choir of the cathedral as early as 1399 until the French Revolution, during which his ashes were scattered to the wind by the Jacobins.
In 1363, at the age of thirteen, having obtained a scholarship, he was admitted as a student to the Collège de Navarre; on 11 April 1381 he earned his doctorate and became a professor of theology; in 1384 he was appointed rector of the Collège de Navarre, and in 1389 chancellor of the University of Paris; in 1391 the king wished to have him as his confessor. The cathedrals of France vied with one another in offering him honors and well-endowed canonries: thus he became canon at Soissons (1375), Noyon (1381), Compiègne (1391), Cambrai (1391), Rouen (1394), and Bayeux (1394), and he accumulated numerous benefices throughout his life, at one point holding fourteen simultaneously. On 2 April 1395, at the hands of Benedict XIII, who knew him personally and held him in high esteem, he was elected bishop of the diocese of Le Puy. In March 1397 he was transferred to the more important see of Cambrai. Later he also served as administrator of the dioceses of Limoges and Orange. Finally, on 19 December 1412, he was created cardinal by John XXIII with the title of S. Crisogono.
Ailly was both a man of learning and a man of action.
As a man of learning, amid his manifold duties, he found time to write numerous works of a scientific, philosophical, theological, and ascetical nature. Currently, 174 of his works are known, and this catalogue may not be complete.
1. In his scientific writings, following the footsteps of Roger Bacon, Ailly dealt with physics, cosmology, geography, astronomy, and even astrology: *Imago mundi; De legibus et sectis contra superstitiones astronomos; De falsis prophetis tractatus duo; Vigintiquatuor quaestiones de concordia astronomicae veritatis cum theologia; Epilogus mappae mundi; Apologia defensiva astronomicae...* are among his principal titles. Among other topics, he also anticipated the correction of the calendar and prepared the ground for the Gregorian reform; he discussed the rotation of the earth on its axis, described its spherical shape, and indicated means to reach the Far East by sea. The *Imago mundi* was certainly in the hands of Christopher Columbus and confirmed him in his ideas, as Columbus himself appears to have declared to the king after his third voyage; evidence of this is provided by a copy annotated by the great navigator now preserved in the Colombina Library in Seville.
2. In his philosophical writings, Ailly was inspired by nominalist principles: as a young man he had nominalist teachers, and his favorite books were the works of William of Ockham, whose teachings he followed particularly on the question of universals and the notion of causality. In the library of Antwerp there is a manuscript by Ailly (1414 pages) containing a complete catalogue of the English philosopher’s works.
3. In his theological writings, he merits recognition for defining the privilege of the Immaculate Conception of Mary and for making excellent observations on biblical exegesis, especially in his *Epistola ad novos Hebraeos*; yet he also erred by almost entirely neglecting the value of tradition and papal documents, following instead the tendencies of nominalist circles. Hence the inaccuracies, rash and paradoxical opinions, and errors found in his works: a) errors regarding God (he denies the evident demonstrability of God’s existence, unity, and fundamental attributes such as omnipotence and freedom); b) regarding the Holy Trinity (he asserts that the doctrine of the Trinity is not evidently contained in either the Old or the New Testament); c) regarding the ultimate end (he claims that the existence of a final end for man is not evident); d) regarding Christian morality (he maintains that there is no act essentially good, no act essentially evil, no act essentially meritorious, nor essentially demeritorious: “nullum est ex se peccatum, sed praecise quia lege prohibitum”); e) regarding the Sacraments (he admits the possibility of “impannation” in the Eucharist); f) above all, he falls into many errors regarding the organization of the Church due to his pronounced tendency to diminish papal authority—a tendency that may perhaps be explained by reflecting on the troubled times in which he lived—he entered public life during the Great Western Schism—and in whose events he took an active part. He maintained that Jesus Christ did not found His Church upon Peter. “Who indeed would establish firmness upon Peter’s weak Church?” The Pope is merely the principal minister of the Church, “principalis inter ministros”; jurisdiction over bishops and priests comes directly from Christ, not from the Pope, who is not necessarily Bishop of Rome, since the primacy was at Antioch before being transferred to the capital of the Roman Empire. It follows that the Pope is not infallible, is subject to a general council, and can be deposed by an ecumenical council, which, though it too can err so that one may appeal from one to the other, must nevertheless be considered superior to the Supreme Pontiff. Only the universal Church is infallible. These errors, which practically prevailed at the Council of Constance, had grave repercussions in later centuries. Wyclif, who claimed to have memorized Ailly’s books, certainly drew upon him for his system of Eucharistic impanation; the reformers of the 16th century claimed to have been inspired by him for several of their doctrines contrary to Catholic teaching; the Gallicans (v. GALLICANISM) then, not without reason, regarded him as their forerunner; even philosophers of the 18th century occasionally appealed to him.
As a man of action, Ailly sincerely loved the Church and worked indefatigably for her. He promoted useful reforms in his diocese of Cambrai; he condemned a sect of false mystics whose leader was a certain William of Hildesheim; he combated the excesses of the flagellants; he served as commissioner in the case of the Dominican Matthew Grabow; but the work to which he devoted his greatest energies was the ending of the Schism. Though he obeyed Clement VII, a cousin of the King of France, in conformity with the entire nation and the University of Paris, he spared no effort to achieve this goal.
More than thirty of his writings were directed to this end; particularly the *Epistola diaboli Leviathan*, the *Invectiva Ezechielis contra Pseudopastores*, the *De materia concilii generalis*, the *Tractatus de potestate ecclesiastica*, the *Tractatus agendorum in concilio generali de Ecclesiae reformatione*, and the *Tractatus super reformatione Ecclesiae in concilio Constantini*. First among all, in the *Epistola diaboli* he outlined around 1381 the “tres viae” for ending the Schism, namely: “arbitral concord,” “resignation by both contenders,” and “a future general council,” though he inclined toward the third, which in fact proved victorious.
In the very heated debates that followed this matter in France, he always worked to reconcile opposing sides, avoiding extreme positions. He opposed the forced abdication that some sought to impose on BENEDICT XIII (1395), as well as the refusal to obey him (1398). After this refusal took hold, he proposed a compromise that was accepted on 30 May 1403, thanks to a careful distinction between the essential papal rights and the accidental papal rights. For this same purpose, A. undertook several embassies: as extraordinary ambassador of WENCESLAUS, King of the Romans, he was sent to the court of Avignon; in 1403 he was again sent to that city as legate of his king; later he was a member of the embassy that went to the two rival popes to persuade them to abdicate, and in 1413 he was legate of JOHN XXIII in Germany. Finally, always to put an end to the division tearing apart the Church, he took part in the Council of Pisa (1409) and in that of Constance (1414). He arrived in Pisa on 7 May and recognized the newly elected ALEXANDER V, but played no significant role there. At Constance, however, where he arrived on 17 November with a retinue of 44 people, his influence was strongly felt. He succeeded in having his principles of conciliar doctrine prevail in the council, definitively abandoned JOHN XXIII, approved the abdication of GREGORY XII, cooperated in the deposition of BENEDICT XIII, and adhered to MARTIN V. Thus he was able to see crowned with success what had been the constant concern of his life.