The persecuting principles which were involved in Luther's system, but which he cared neither to develop, to apply, nor to defend, were formed into a definite theory by the colder genius of Melanchthon. Destitute of Luther's confidence in his own strength, and in the infallible success of his doctrine, he clung more eagerly to the hope of achieving victory by the use of physical force. Like his master he too hesitated at first, and opposed the use of severe measures against the Zwickau prophets; but when he saw the development of that early germ of dissent, and the gradual dissolution of Lutheran unity, he repented of his ill-timed clemency.[235] He was not deterred from asserting the duty of persecution by the risk of putting arms into the hands of the enemies of the Reformation. He acknowledged the danger, but he denied the right. Catholic powers, he deemed, might justly persecute, but they could only persecute error. They must apply the same criterion which the Lutherans applied, and then they were justified in persecuting those whom the Lutherans also proscribed. For the civil power had no right to proscribe a religion in order to save itself from the dangers of a distracted and divided population. The judge of the fact and of the danger must be, not the magistrate, but the clergy.[236] The crime lay, not in dissent, but in error. Here, therefore, Melanchthon repudiated the theory and practice of the Catholics, whose aid he invoked; for all the intolerance in the Catholic times was founded on the combination of two ideas--the criminality of apostasy, and the inability of the State to maintain its authority where the moral sense of a part of the community was in opposition to it. The reformers, therefore, approved the Catholic practice of intolerance, and even encouraged it, although their own principles of persecution were destitute not only of connection, but even of analogy, with it. By simply accepting the inheritance of the mediaeval theory of the religious unity of the empire, they would have been its victims. By asserting that persecution was justifiable only against error, that is, only when purely religious, they set up a shield for themselves, and a sword against those sects for whose destruction they were more eager than the Catholics. Whether we refer the origin of Protestant intolerance to the doctrines or to the interests of the Reformation, it appears totally unconnected with the tradition of Catholic ages, or the atmosphere of Catholicism. All severities exercised by Catholics before that time had a practical motive; but Protestant persecution was based on a purely speculative foundation, and was due partly to the influence of Scripture examples, partly to the supposed interests of the Protestant party. It never admitted the exclusion of dissent to be a political right of the State, but maintained the suppression of error to be its political duty. To say, therefore, that the Protestants learnt persecution from the Catholics,