ARNALDO of Brescia. - Born at the end of the 11th century or the beginning of the following one in Brescia, he began an ecclesiastical career, but it is doubtful whether he advanced beyond minor orders. Of his youth, only his journey to Paris and his stay at the school of Abelard are known, of whom he became the most devoted disciple and the warmest defender. After 1119 he returned to his homeland and took part in the struggles agitating his city against the simoniacal clergy and the temporal authority of the bishop. At that time the consequences of the investiture controversy were being felt everywhere and were agitating not only the clergy but above all the lower classes of the cities, who made of the moral question an argument for political rebellion. In Brescia, Bishop Villani was favourable to the antipope Anacletus II, while the consuls sided with Innocent II; the bishop was replaced by Manfredi, favourable to reform, who, however, after an uprising, was expelled from the city. Meanwhile, A., having gone much further in his anticlerical stance, which struck at the entire Catholic hierarchical system, was denounced to the Pope for his rebellious conduct and condemned at the Second Lateran Council of 1139. He then returned to France, but here he threw himself into the very lively disputes between Abelard and St Bernard, supporting the former; for this he was condemned with him at the Council of Sens and confined to a monastery. Soon after he was able to open a school of moral theology on the mountain of St Genevieve, where he resumed his invectives against the worldliness of the clergy, but with little success. Through the efforts of St Bernard, who also sought the help of the King of France, he was expelled and took refuge in Switzerland with the Augustinian canons of Zurich; he also enjoyed for a time the protection of the Bishop of Constance, but then St Bernard succeeded in exposing him, and he had to leave. A. however had a friend in Cardinal Guido of Castello, then papal legate in Bohemia, and was able to remain with him quietly; there he met Gerho of Reichersberg, who recommended him to Celestine II. Perhaps following the cardinal, A. came to Italy and around 1145 arrived in Rome. The conditions of the city in those years were very troubled, since the *renovatio senatus* had taken place, the restoration of civic autonomy with a distinctly antipapal character and the predominance of popular elements. Some popes who had tried to oppose the movement had come to a bad end, others had left Rome. At first A. was a stranger to the political struggles. After abjuring his errors before Pope Eugenius III in Viterbo, he was (it seems) sent by him to Rome in penitential garb to make an expiatory pilgrimage. Soon, however, political passion took hold of him again, and he began to preach once more, quickly gathering wide support around him. The object of his discourses was still only the reform of ecclesiastical morals, the call to a more ascetic life in conformity with evangelical ideals. Yet it was inevitable that an understanding should be established between the two movements, A.'s religious one and that of the Roman senate, given their affinity of programmes, the common enemy to be fought and the identity of the historical appeals to which both appealed. The point of agreement came when A. proclaimed that ecclesiastics should not possess temporal goods, that all these belonged to the laity and therefore to the prince. The clash between the Pope and the rebel took on notable harshness: Adrian IV demanded A.'s expulsion, the senate refused, pledging to guarantee his safety, while A. swore to defend the republic with his word; in an uprising a cardinal was wounded, and then the Pope launched an interdict on the city. A. had to flee from Rome, but at this point a new protagonist entered the scene and his action was decisive: Frederick Barbarossa, recently raised to the empire and deeply convinced of his duties as armed defender of the Church, was only too glad to do a service to the Pope, with whom he had many other grounds of contention. Thus A. was seized by the partisans of Barbarossa and handed over to the city prefect Peter, who condemned him to death; it is very probable that he was hanged and then burned. His ashes were thrown into the Tiber so that they might not become an object of veneration by the numerous and convinced followers who still remained in Rome after his death.
It has been rightly observed that A.'s criticisms of worldly clergy are no more severe or violent than those of St Peter Damian, and that in the end he and his great adversary St Bernard were fighting the same vices in apparently similar forms. And yet the difference between the two is truly radical and explains the difference in their success. It is impossible to distinguish how much was personal in A.'s preaching and how much he repeated concepts and aspirations common to wide sections of the people. Without doubt he was very learned, of lively intelligence, a warm speaker; he led an austere life and knew how to instil his feelings in many; he wrote little or nothing.