In 1523 a papal appeal to Zürich to abandon Zwingli was answered by the canton's formal declaration of independence from the Catholic Church. Henceforth the revolt spread rapidly throughout Switzerland, except in the five forest cantons, the very heart of the country, where the ancient religion was still deeply intrenched. Serious efforts were made to join the followers of Zwingli with those of Luther, and thus to present a united front to the common enemy, but there seemed to be irreconcilable differences between Lutheranism and the views of Zwingli. The latter, which were succinctly expressed in sixty-seven Theses published at Zürich in 1523, insisted more firmly than the former on the supreme authority of Scripture, and broke more thoroughly and radically with the traditions of the Catholic Church. Zwingli aimed at a reformation of government and discipline as well as of theology, and entertained a notion of an ideal state in which the democracy would order human activities, whether political or religious. Zwingli differed essentially from Luther in never distrusting "the people." Perhaps the most distinctive mark of the Swiss reformer's theology was his idea that the Lord's Supper is not a miracle but simply a symbol and a memorial. In 1531 Zwingli urged the Protestant Swiss to convert the five forest cantons to the new religion by force of arms. In answer to his entreaties, civil war ensued, but the Catholic mountaineers won a great victory that very year and the reformer himself was killed. A truce was then arranged, the provisions of which foreshadowed the religious settlement in the Germanies--each canton was to be free to determine its own religion. Switzerland has remained to this day part Catholic and part Protestant. [Sidenote: Calvin] By the sudden death of Zwingli, Swiss Protestantism was left without a leader, but not for long, because the more celebrated Calvin took up his residence in Geneva in 1536. From that time until his death in 1564 Calvin was the center of a movement which, starting from these small Zwinglian beginnings among the Swiss mountains, speedily spread over more countries and affected more people than did Lutheranism. In Calvinism, Catholicism was to find her most implacable foe. John Calvin, who, next to Martin Luther, was the most conspicuous Protestant leader of the sixteenth century, was a Frenchman. Born of middle-class parentage at Noyon in the province of Picardy in 1509, he was intended from an early age for an ecclesiastical career. A pension from the Catholic Church enabled him to study at Paris, where he displayed an aptitude for theology and literature. When he was nineteen years of age, however, his father advised him to abandon the idea of entering the priesthood in favor of becoming a lawyer--so young Calvin spent several years studying law. [Sidenote: Calvin in France]