AILLY, PIERRE D, (1350-1420), French theologian, was born at Compiegne in 1350 of a bourgeois family, and studied in Paris at the celebrated college of Navarre. He became a licentiate of arts in 1367, procurator of the French "nation" in 1372, bachelor of theology in 1372, and licentiate and doctor in that faculty in 1381.
Since 1378 Western Christendom, in consequence of the election of the two popes Urban VI. and Clement VII., had been divided into two obediences. In the spring of 1379 Pierre d'Ailly, in anticipation even of the decision of the university of Paris, had carried to the pope of Avignon the "role" of the French nation, but notwithstanding this prompt adhesion he was firm in his desire to put an end to the schism, and when, on the 20th of May 1381, the university decreed that the best means to this end was to try to gather together a general council, Pierre d'Ailly supported this motion before the king's council in the presence of the duke of Anjou. The dissatisfaction displayed shortly after by the government obliged the university to give up this scheme, and was probably the cause of Pierre d'Ailly's temporary retirement to Noyon, where he held a canonry. There he continued the struggle for his side in a humorous work, in which the partisans of the council are amusingly taken to task by the demon Leviathan.
After his return to Paris, where from 1384 onwards he filled the position of master of the college of Navarre, and took part in a violent campaign against the chancellor of Notre-Dame, he was twice entrusted with a mission to Clement VII. in 1388 to defend the doctrines of the university, and especially those concerning the Immaculate Conception of the Virgin, against the preaching friar Jean de Montson, and in 1389 to petition in the name of the king for the canonization of the young cardinal Peter of Luxemburg. The success which attended his efforts on these two occasions, and the eloquence which he displayed, perhaps contributed to his choice as the king,s almoner and confessor. At the same time, by means of an exchange, he obtained to the highest dignity in the university, becoming chancellor of Notre-Dame de Paris.
When in 1394 Benedict XIII. succeeded Clement VII. at Avignon, Pierre d'Ailly was entrusted by the king with a mission of congratulation to the new pontiff. His obsequious language on this occasion, and the favours with which it was rewarded, formed a too violent contrast to the determined attitude of the university of Paris, which, tired of the schism, was even then demanding the resignation of the two pontiffs. Pierre d'Ailly himself had not long before taken part in the drawing up of a letter to the king in which the advantages of this double abdication were set forth, but since then his zeal had seemed to cool a little. None the less, on his return from Avignon, he again in the presence of the king enlarged upon the advantages offered by the way which the university commended. But the suspicions aroused by his conduct found further confirmation when he caused himself-or allowed himself-to be nominated bishop of Le Puy by Benedict XIII. (April 2, 1395 ). The great number of benefices which he held left room for some doubt as to his disinterestedness. Henceforward he was under suspicion at the university, and was excluded from the assemblies where the union was discussed.
Some time afterwards Pierre d'Ailly became bishop of Cambrai (March 19, 1397) by the favour of the pope, who had yielded no whit, and, by virtue of this position, became also a prince of the empire. In order to take possession of his new see, he had to brave the wrath of the duke of Burgundy, override the resistance of the clergy and bourgeoisie, and even withstand an armed attack on the part of several lords; but his protector, the duke of Orleans, had his investiture performed by Wenceslaus, king of the Romans. The latter, though a partisan of the pope of Rome, took the opportunity of enjoining on Pierre d'Ailly to go in his name and argue with the pope of Avignon, a move which had as its object to persuade Benedict XIII. to an abdication, the necessity of which was becoming more and more evident. However, the language of the bishop of Cambrai seems on this occasion to have been lacking in decision; however that may be, it led to no felicitous result.
France next tried to bring violent pressure to bear to conquer the obstinacy of Benedict XIII. by threatening a formal withdrawal from his obedience. Pierre d'Ailly, who, in spite of his attachment to the pope, had been carried away by the example of the kingdom, was among the first who, in 1403, after experience of what had happened, counselled and celebrated the restoration of obedience. He was sent by Charles VI. on an embassy to Benedict XIII. and seized this opportunity of lavishing on the pontiff friendly congratulations mingled with useful advice. Two years later, before the same pontiff, he preached in the city of Genoa a sermon which led to the general institution, in the countries of the obedience of Avignon, of the festival of the Holy Trinity.
At the ecclesiastical council which took place at Paris in 1406 Pierre d'Ailly made every effort to avert a new withdrawal from the obedience and, by order of the king, took the part of defender of Benedict XIII., a course which yet again exposed him to attacks from the university party. The following year he and his disciple Gerson formed part of the great embassy sent by the princes to the two pontiffs, and while in Italy he was occupied in praiseworthy but vain efforts to induce the pope of Rome to remove himself to a town on the Italian coast, in the neighbourhood of his rival, where it was hoped that the double abdication would take place. Discouraged by his failure to effect this, he returned to his diocese of Cambrai at the beginning of 1408. At this time he was still faithful to Benedict XIII., and the disinclination he felt to joining the members of the French clergy who were on the point of ratifying the royal declaration of neutrality excited the anger of Charles VI.'s government, and a mandate, which was however not executed, ordered the arrest of the bishop of Cambrai.
It was not till after the cardinals of the two colleges had led to the convocation of the general council of Uisa that Tierre d'Aiily renounced the support of Benedict XIII., and, for want of a better policy, again allied himself with the cause which he had championed in his youth. In the council lay now, to judge from his words, the only chance of salvation; and, in view of the requirements of the case, he began to argue that, in case of schism, a council could be convoked by any one of the faithful, and would have the right to judge and even to depose the rival pontiffs. This was, in fact, the procedure of the council of Pisa, in which Pierre d'Ailly took part. After the declaration of the deposition of Gregory XII. and Benedict XIII. it went on to the election of Alexander V. (June 26th, 1409), This pope reigned only ten months; his successor, John XXIII., raised Pierre d'Ailly to the rank of cardinal (June 6, 1411), and furtuer, to indemnify him for the loss of the bishopric of Cambrai, conferred upon him the administration of that of Limoges (November 3, 1412), which was shortly after exchanged for the bishopric of Orange. He also nominated Pierre d'Ailly as his legate in Germany (March 18, 1413).
Forgetting these benefits, the cardinal of Cambrai was one of the most formidable adversaries of John XXIII. at the council of Constance. Convinced as he was of the necessity for union and reform, he contributed more than any one to the adoption of the principle that, since the schism had survived the council of Pisa, it was necessary again to take up the work for a fundamental union, without considering the rights of John XXIII. any more than they had those of Gregory XII. and Benedict XIII. From this point of view Pierre d'Ailly, together with his compatriot Cardinal Fillastre, took the preponderating part during the first few months. Afterwards, seeing the trend of events, he showed some uneasiness and hesitation. He refused, however, to undertake the defence of John XXIII., and only appeared in the trial of this pope to make depositions against him, which were sometimes of an overwhelming character.
Among the important matters which claimed his attention at Constance may be mentioned also the condemnation of the errors of Wycliffe and the trial of John Huss. The reading in public of his two treatises De Potestate ecclesiastica and De Reformalione Ecclesiae revealed, besides ideas very peculiar to himself on the reform and constitution of the church, his design of reducing the power of the English in the council by denying them the right of forming a separate nation (October 1-November 1, 1416). By this campaign, which exposed him to the worst retaliation of the English, he inaugurated his role of "procurator and defender of the king of France."
When at last the question arose of giving the Christian world a new pope, this time sole and uncontested, Pierre d'Ailly defended the right of the cardinals, if not to keep the election entirely in their own hands, at any rate to share in the election, and he brought forward an ingenious system for reconciling the pretensions of the council with the rights of the Sacred College. In this way was elected Pope Martin V. (November 11, 1417), and the task of Pierre d'Ailly was at last finished.
The predominance of the Anglo-Burgundians in France having made it impossible for him to stay there, he went to Avignon to end his days in melancholy calculations arising from the calamities of which he had been the witness, and the astrological reckonings, in which he found pleasure, of the chances for and against the world coming to an end in the near future. He died on the 9th of August 1420.
Pierre d'Ailly's written works are numerous. A great part of them was published with the works of Gerson (by Elhes du Pin, Antwerp, 1706); another part appeared in the 15th century, probably at Brussels, and there are many treatises and sermons still unpublished. In philosophy he was a nominalist. Many questions in science and astrology, such as the reform of the calendar, attracted his attention. His other works consisted of theological essays, ascetic or exegetic, questions of ecclesiastical discipline and reform, and of various polemical writings called forth for the most part by the schism.
Whatever reservations may be made as to a certain interested or ambitious side of his character, Pierre d'Ailly, whose devotion to the cause of union and reform is incontestable, remains one of the leading spirits of the end of the 14th and beginning of the 15th centuries.
BIBLIOGRAPHY.-P. Tschackert, Peter van Ailli (Gotha, 1877); L. Salembier, Petrus de Alliaco (Lille, 1886); H. Denifle et Em. Chatelain, Chartularium Universitatis Parisiensis, t. iii. (Paris, 1894); N. Valois, La France et le Grand Schisme d'Occident (Paris, 4 vols., 1896-1902); and Bibliotheque de l'ecole des chartes, vol. lxv., 1904, pp. 557-574. (N. V.)
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)