Heresy--the refusal to accept the teaching of the Church--was the one unpardonable sin, a moral leprosy worse in mediaeval eyes than any human disease because it affected the soul, not the body, and the life of the soul was everlasting. The heretic must be suppressed, converted if possible, but if not, burned and forgotten like a diseased rag, lest his wrong beliefs should infect others and so lose their souls also eternally. To-day we know that neither suppression nor burnings can ultimately extinguish that independence of thought and spirit of inquiry that are as much the motive power of some human natures as the acceptance of authority is of others. Tolerance, and how far it can be extended to actions as well as beliefs, is one of the problems that the world is still studying. The towns and provinces, where the first battles were fought, are sown with the blood and ashes of those who neither sought nor offered the way of compromise as a solution. Another of Abelard’s pupils, besides the orthodox Peter Lombard, was an Italian, Arnold of Brescia--in many ways a man of like intellect with his master, self-centred, restless, and ambitious. When he returned home from the University he at once took a violent part in the life of the Brescian commune, declaring publicly that the Church should return to the days of ‘apostolic poverty’, and urging the citizens to cast off the yoke of their bishop. Exiled from Italy by the anger of the Pope and clergy at his views he went again to Paris, where he taught in the University until by the King’s command he was driven away. He next found a refuge in Germany under the protection of a papal legate, who had known and admired him in earlier days; but this news aroused the furious anger of St. Bernard. ‘Arnold of Brescia,’ he wrote to the legate, ‘whose speech is honey ... whose doctrine poison, the man whom Brescia has vomited forth, whom Rome abhors, whom France drives into exile, whom Germany curses, whom Italy refuses to receive, obtains thy support. To be his friend is to be the foe of the Pope and God.’