That all the five books were composed by one author is not probable; perhaps originally only the Acts of John bore the name of Leucius, which was subsequently transferred to the whole. Zahn’s view, on the other hand, is, that the Περίοδοι τῶν ἀποστόλων, especially the _Acts of John_, was written under the falsely assumed name of John’s pupil Leucius, about A.D. 130, at a time when the Gnostics had not yet been separated from the Church as a heretical sect, was even at a later period accepted as genuine by the Catholic church teachers notwithstanding the objectionable character of much of its contents, its modal docetic Christology and encratite Ethics with contempt of marriage, rejection of animal food and the use of wine and the demand of voluntary poverty, and held in high esteem as a source of the second rank for the Apostolic history. Lipsius considers that it was composed in the interests of the vulgar Gnosticism (§ 27) in the second half of the 2nd, or first half of the 3rd cent., and proves that from Eusebius down to Photius, who brands it as πασῆς αἱρέσεως πηγὴν καὶ μητέρα, the Catholic church teachers without exception speak of it as heretical and godless, and that the frequent patristic references to the _Historiæ ecclesiasticiæ_ do not apply to it but to Catholic modifications of it, which were regarded as the genuine and generally credible original writing of Leucius which were wickedly falsified by the Manichæans.--Catholic modifications of particular Gnostic Περίοδοι, as well as independent Catholic writings of this sort in Greek are still preserved in MS. in great numbers and have for the most part been printed. The _Hist. certaminis apostolici_ in ten books, which the supposed pupil of the Apostles Abdias, first bishop of Babylon, wrote in Hebrew, was translated by his pupil Eutropius into Greek and by Julius Africanus into Latin.[87]--They are all useless for determining the history of the Apostolic Age, although abundantly so used in the Catholic church tradition. For the history of doctrines and sects, the history of the canon, worship, ecclesiastical customs and modes of thought during the 2nd-4th cents., they are of the utmost importance. § 32.6. From the many apocryphal monographs still preserved on the life, works and martyrdom of the biblical Apostles and their coadjutors, in addition to the Pseudo-Clementines already discussed in § 28, 3, the following are the most important.