Pope and Emperor strove at once to embody their theories in acts. The proceedings of the anti-papal synod of Reims were annulled; its nominee to the see of Reims, Gerbert of Aurillac, was forced to yield up his post to the worldly Arnulf that the synod strove in vain to depose. The whole French episcopate bowed in submission before the new Pope, and Gerbert soon repudiated his earlier teachings. The French king, Robert, was visited with the severest censures of the Church for contracting a marriage within the prohibited degrees. The holy Adalbert, the apostle of Bohemia, but driven from his see of Prague by a pagan reaction, was sternly ordered to return to his bishopric, or, if that were impossible, to engage in a new mission to the heathen. Adalbert chose the latter alternative, and his early death at the hands of the heathen Prussians made him the protomartyr of the new order that Otto and Gregory were striving to introduce. But while the two enthusiasts were busy in the regeneration of the universe, they were unable to maintain themselves in the very centre of their power. A new Roman rebellion brought back Crescentius. [Sidenote: Fall of Crescentius, 998.] Only through the help of the iron soldiery of the Saxon borders, headed by the valiant Eckhard of Meissen, could Otto win back the Eternal City to his obedience. In 998 Rome surrendered, and Crescentius atoned for his rebellion on the scaffold. [Sidenote: Gerbert of Aurillac.] An early death now cut off Gregory V., and Otto raised Gerbert of Aurillac[3] to the papal throne. Gerbert was quite the most remarkable man of his age. A poor Frenchman of obscure birth from the uplands of the centre, he received his first schooling in a cloister at his native Aurillac, where he took the monastic vows. Borrel, a pious Count of Barcelona, made his acquaintance while visiting Aurillac on a pilgrimage, and took him back with him to the Spanish march. There Gerbert abode some years, and there he acquired that profound knowledge of mathematics which had perhaps filtered into the march from the Mussulman schools of Cordova, and which gave him in the unlearned north a reputation for extraordinary learning, if not for magical skill. Ever eager for knowledge, he accompanied his patron to Italy, and attracted the notice of Otto I. Finally he settled down at Reims, attracted by the fame of a certain archdeacon who taught in the cathedral school. The good Archbishop Adalbero made Gerbert ‘scholasticus’ of the school at Reims. Accompanying the archbishop to Italy, Gerbert received from Otto II. the headship of Columban’s old abbey of Bobbio, and speedily reformed its lax discipline. On Otto II.’s death, the angry monks drove him away, and he went back to Reims and resumed his teaching as ‘scholasticus.’ He dominated the policy of the archbishop in the critical years that saw the accession of Hugh Capet to the French throne [see pages 70–71], but on Adalbero’s death was ungratefully passed over