A German monk, theologian and University professor, the initiator of the Reformation of the Church and the father of Protestantism. At the start, Luther was indignant with the German preachers who, in order to help Pope Leo X continue the construction of the Saint Peter basilica in Rome, offered the faithful, in return for money, ‘indulgences’, in other words a remission of the punishments which sanctioned sins. He denounced the very principle of this practice in his 95 Theses (1517). At this point in time he did not yet wish to leave the Roman Catholic Church, but solely to battle against its abuses and contribute to its reform. But the Pope did not see things in the same light: he condemned him as a heretic in 1520 and excommunicated him in 1521. Summoned to Worms (Rhineland-Palatinate) to appear before the Diet (in other words the general assembly of the states) of the Germanic Holy Roman Empire, he refused to retract, estimating himself subject to the authority of the Bible rather than that of the Catholic hierarchy. He was thus banished from the Empire; his books were banned and burned. Taken into his castle by his friend, the Elector of Saxony Frederick the Wise III, he there wrote his best known works, which were widely disseminated thanks to the development of ‘modern’ printing, created by Johannes Gutenberg. Luther devoted the whole of the end of his life elaborating his theology and constructing his Church. His Reform marked a wish to return to the sources of Christianity, in opposition to the directions taken by the Church during the Middle Ages. Referring to the Bible – and not to the Papal hierarchy – as the sole legitimate source of religious authority was one of the fundamental elements of the Reformation. The question of the salvation of souls as a gift granted by God was equally central to the thinking of the reformers, who denounced the corruption of society brought about by the trade in indulgences. Undertaken by Martin Luther in Germany and Ulrich Zwingli in Switzerland, relayed with particular accents by John Calvin in Geneva and France, the Reformation would extend throughout the whole of North West Europe. The Counter Reformation carried out by the Catholic Church would permit it only a partial winning back of the people won over to Protestantism. In the 16th century, the battles of influence between Catholics and the Reformed would be expressed through numerous conflicts in the Germanic world and by civil wars in France, England and Scotland.