Summarizing the Greek influence, both Hellenic and Graeco-oriental, upon Christian hymnology, it is difficult, if not impossible, to trace any connection between the classic Greek hymns or the hymns of mystery cults, and those of the new faith. If more sources were available, a valid conclusion might be reached. At present, a tentative conclusion involves the recognition of the vigorous protest and revolt against pagan ideas revealed in contemporary prose writings, in turn evoked by the actual pressure which was exerted upon Christianity by alien cults. The twentieth century has produced an impressive literature centered about the mystery religions and the problem of their influence upon Christianity; but in the field of hymnology there have been discovered only the faintest of traces. These are wholly stylistic. Christian hymns which reveal the characteristics of the repetition of direct address, or of relative clauses or predicates, previously mentioned, illustrate poetic forms which are, in the final analysis, oriental rather than Greek.[53] It is a satisfaction to the classicist, who is interested in the history of this subject, that the classical meters, ignored at this period, were destined to be revived at a later date. They were used to some extent from the fourth century. It was reserved for the court poets of the Carolingian circle of the ninth century to restore the old lyric meters. The Sapphic meter in its Horatian form not only was a favorite among medieval Latin hymn writers, but also it has found an occasional imitator in the course of the centuries even to modern times.[54]