These and other points which the post-Christian Gnostic sects seem to have had in common[67] can therefore be accounted for by their common origin, without accepting the theory of the textual critics that the Fathers had been deceived by an impostor who had made one document do duty several times over. Yet until we have the writings of the heresiarchs actually in our hands, we must always be in doubt as to how far their opinions have been correctly recorded for us. The post-Christian Gnostic sects have been compared with great aptness to the Protestant bodies which have sprung up outside the Catholic Church since the German Reformation[68], and the analogy in most respects seems to be perfect. Yet it would probably be extremely difficult for a bishop of the Church of Rome or of that of England to give within the compass of an heresiology like those quoted above an account of the tenets of the different sects in England and America, without making grave and serious mistakes in points of detail. The difficulty would arise from want of first-hand knowledge, in spite of the invention of printing having made the dissemination of information on such subjects a thousand times more general than in sub-Apostolic times, and of the fact that the modern sects, unlike their predecessors, do not seek to keep their doctrines secret. But the analogy shows us another cause of error. The “Free Churches,” as they are called in modern parlance, have from the outset shown themselves above all things fissiparous, and it is enough to mention the names of Luther, Zwingli, Calvin, Socinus, Wesley, and Chalmers to show how hopelessly at variance the teachings of the founders of sects at first sight are. But in spite of this, there seems to have been always a sort of fluidity of doctrine among them, and hardly any of the Nonconformist sects now profess the dogmas with which they first came into existence. The changes in this respect, however, never involve the borrowing of new tenets from sources external to them all, but seem to be brought about by a sort of interfiltration between one sect and another. Thus, for example, for many centuries after the Reformation the majority of the dissident sects which rejected all connection with the Catholic Church were among the stoutest defenders of the Divinity of Jesus, and the Socinians who held the contrary opinion were in an entirely negligible minority. At the present day, however, the tendency seems to run the other way, and many Nonconformist bodies are leaning towards Unitarian doctrines, although few of them probably have ever heard the name of Socinus. A similar tendency to interpenetration of doctrines early showed itself among the Gnostics; and there can be little doubt that it sometimes led to a fusion or amalgamation between sects of widely differing origin. Hence it is not extraordinary that certain tenets are sometimes recorded by the Fathers as peculiar to one Gnostic leader and sometimes to another, and to trace