Finally, we gather much of our knowledge from the controversial treatises of the early Christian Fathers, written with propagandist zeal in the heat of their struggle against Paganism. They reveal to us much of the religion that they strove to overthrow by the exposure of its viciousness and its absurdities. But their statements must be used with cautious criticism. Their knowledge was by no means always at first hand, unless--which we rarely know to have been the case--they were, like Clemens of Alexandria, converted Pagans who had been bred up in the Græco-Roman polytheism. Their statements, for instance, about the Greek mysteries are often vague and unconvincing, while in their desire to include them all in one general condemnation they confuse Anatolian rites with Eleusinian. And they are pardonably blind to the often beautiful ritual, the nobler ideas and the higher moral elements in the older Mediterranean religions. Nevertheless, if we make due allowance for prejudice and exaggeration, works such as the _Protreptica_ of Clemens, the treatise of Arnobius, _Adversus Gentes_, of Firmicus Maternus, _De Errore Profanarum Gentium_, Eusebius’ _Præparatio Evangelica_, Augustine’s _De Civitate Dei_, Athenagoras’ _Legatio_, must be ranked among the primary sources of our history. A special but very important chapter in the later history of Greek religion is the account of the growth and diffusion of the religious brotherhoods, especially the Orphic Dionysiac societies. For these we have something of direct liturgical evidence in the {14} collection of Orphic hymns, mainly the products of the later theosophic period, but throwing light on the theology and ritual of these sects. But our knowledge of this mystic religion which was engrafted upon Hellenism has been in recent times enriched by the priceless discovery of an ancient poetical Orphic liturgy engraved upon gold-leaf found in tombs of Crete and South Italy and probably a product of the fifth century B.C.