Book X seems at first sight likely to solve many of the questions which every reader who has got so far is compelled to ask. It begins, in accordance with the habit just noted, with the statement that the author has now worked through “the Labyrinth of Heresies” and that the teachings of truth are to be found neither in the philosophies of the Greeks, the secret mysteries of the Egyptians, the formulas of the Chaldæans or astrologers, nor the ravings of Babylonian magic.[60] This links it with fair closeness to the reference in Book IV to the ideas of the Persians, Babylonians, Egyptians and Chaldæans, only the first-named nation being here omitted from the text. It then goes on to say that “having brought together the opinions[61] of all the wise men among the _Greeks_ in four books and those of the heresiarchs in five,” he will make a summary of them. It will be noted that this is in complete contradiction to the supposition that the missing Books II and III contained the doctrines of the Babylonians, as he now says that they comprised those of the Greeks only. The summary which follows might have been expected to make this confusion clear, but unfortunately it does nothing of the kind. It does indeed give so good an abstract of what has been said in Books V to IX inclusive regarding the chief heresiarchs, that in one or two places it enables us to correct doubtful phrases and to fill in gaps left in earlier books. There is omitted from the summary, however, all mention of the heresies of Marcus, Satornilus, Menander, Carpocrates, the Nicolaitans, Docetæ, Quartodecimans, Encratites and the Jewish sects, and the list of omissions will probably be thought too long to be accounted for on the ground of mere carelessness. But when the summarizer deals with the earlier books, the discrepancy between the summary and the documents summarized is much more startling. Among the philosophers, he omits to summarize the opinions of Pythagoras, Empedocles, Ecphantus, Hippo, Socrates, Plato, Aristotle, the Stoics, Academics, Brachmans, or Druids, while he does mention those of Hippasus, Ocellus Lucanus, Heraclides of Pontus and Asclepiades, who were not named in any of the texts of Book I which have come down to us. As for the tenets and practices of the Persians, Egyptians and others, supposed on the strength of the statement at the beginning of Book V to have been narrated in Books II and III, nothing further is here said concerning them, and, by the little table of contents with which Book X like the others is prefaced, it will appear that nothing was intended to be said. For this last omission it might be possible to assign plausible reasons if it stood alone; but when it is coupled with the variations between summary and original as regards Book I, the only inference that meets all the facts is that the summarizer did not have the first four books under his eyes.