as a purely religious matter, but also as a social danger. Another phenomenon which conservatives naturally viewed with misgiving was early translations of the Scriptures into the vernacular. Parallel to the peril of revolution from social ideas among the servile classes of the community was that of the ‘open’ Bible among the ignorant, uninstructed laity. For many reasons, then, the conservatives were prompted to be cautious. Their heroic attempt to secure reform from within—made in the great Conciliar movement—definitely failed. It failed in the main because it was not sufficiently drastic, and because, while it healed the Schism, it did not secure the moral elevation of the papacy. The Council of Basel proposed the most elaborate measures for reform; but they were never confirmed by the papacy. The loftiest aspirations were represented within the Church. They had always been. The Canon law had been clear and unequivocal enough on the subject of clerical conduct. The difficulty lay in making these aspirations, reflected alike in the Canon law and in the proposals of the Councils, thoroughly effective. The history of mediæval heresy takes us as far as the Conciliar movement. There we stand on the threshold of the modern world, the scene changes, with new actors and a new atmosphere. The Protestant Reformation is much more familiar than the earlier movements. Yet the subject of these is one of great and manifold interest. For the heresies of the Middle Ages were of various types and arose from a variety of causes. Broadly speaking, we may say that any circumstances which tended to break up the unity of the _Civitas Dei_, whether in the sphere of action or of theory, might be productive of heresy. That is obviously a very rough generalization indeed; but only broad generalization can include such diverse sources of heresy as the obsessions of fanatics like Eon de l’Etoile and Dolcino, the dialectical disputations of theologians like Roscellinus and philosophers like Siger, the anti-sacerdotalism of Waldenses and Cathari, the profounder searchings of heart and mind that inspired the revolts of Wycliffe and Hus. Nor must we forget the influence of the political factor, the contention between papacy and secular princes regarding rights and jurisdiction, which was a potent encouragement to controversy. Such strife, where in theory there should have been complete harmony, was in itself productive of doubt and unsettlement. The very heinousness of heresy to the mediæval mind lay largely in its challenge to the essential social, ecclesiastical, doctrinal unity of Christendom. Whether the springs of its being were an emotional afflatus, a moral revulsion, or an intellectual ferment, heresy was in any case a challenge to the existing order. Its adherents were always a comparatively small and unpopular minority. Society as a whole regarded it as dangerous and was convinced of the necessity of its repression.