We have ample evidence also as to the state of Christian thought in the post-Nicene period. The Fathers Athanasius, Basil, Gregory of Nazianzus, Gregory of Nyssa, and Cyril of Jerusalem, the decrees of general and local Councils, the apocryphal and pseudonymous literature, enable us to form a clear conception of the change which Greek influences had wrought. But the evidence as to the mode in which the causes operated within the Christian sphere before the final effects were produced is singularly imperfect. If we look at the literature of the schools of thought which ultimately became dominant, we find that it consists for the most part of some accidental survivals.[2] It tells us about some parts of the Christian world, but not about others. It represents a few phases of thought with adequate fulness, and of others it presents only a few fossils. In regard to Palestine, which in the third and fourth centuries was a great centre of culture, we have only the evidence of Justin Martyr. In regard to Asia Minor, which seems to have been the chief crucible for the alchemy of transmutation, we have but such scanty fragments as those of Melito and Gregory of Neocæsarea. The largest and most important monuments are those of Alexandria, the works of Clement and Origen, which represent a stage of singular interest in the process of philosophical development. Of the Italian writers, we have little that is genuine besides Hippolytus. Of Gallican writers, we have chiefly Irenæus, whose results are important as being the earliest formulating of the opinions which ultimately became dominant, but whose method is mainly interesting as an example of the dreary polemics of the rhetorical schools. Of African writers, we have Tertullian, a skilled lawyer, who would in modern times have taken high rank as a pleader at the bar or as a leader of Parliamentary debate; and Cyprian, who survives chiefly as a champion of the sacerdotal hypothesis, and whose vigorous personality gave him a moral influence which was far beyond the measure of his intellectual powers. The evidence is not only imperfect, but also insufficient in relation to the effects that were produced. Writers of the stamp of Justin and Irenæus are wholly inadequate to account for either the conversion of the educated world to Christianity, or for the forms which Christianity assumed when the educated world had moulded it.