suppose that our text was published anonymously or pseudonymously, the natural inference is that both Hippolytus and Theodoret drew from a common source. What this source was likely to have been there can be little doubt. Our author speaks more than once of “the blessed elder Irenæus,” who has, he says, refuted the heretic Marcus with much vigour, and he implies that the energy and power displayed by Irenæus in such matters have shortened his own work with regard to the Valentinian school generally.[39] Photius, also, writing as has been said in the ninth century, mentions a work of Hippolytus against heresies admittedly owing much to Irenæus’ instruction. The passage runs thus:-- “A booklet of Hippolytus has been read. Now Hippolytus was a disciple of Irenæus. But it (i. e. the booklet) was the compilation against 32 heresies making (the) Dositheans the beginning (of them) and comprising (those) up to Noetus and the Noetians. And he says that these heresies were subjected to refutations by Irenæus in conversation[40] (or in lectures). Of which refutations making also a synopsis, he says he compiled this book. The phrasing however is clear, reverent and unaffected, although he does not observe the Attic style. But he says some other things lacking in accuracy, and that the Epistle to the Hebrews was not by the Apostle Paul.” These words have been held by Salmon and others to describe the tractate _Adversus Omnes Hæreses_. Yet this tractate contains not thirty-two heresies, but twenty-seven, and begins with Simon Magus to end with the Praxeas against whom Tertullian wrote. It also notices another heretic named Blastus, who, like Praxeas, is mentioned neither by Irenæus nor by our author, nor does it say anything about Noetus or the Apostle Paul. It does indeed mention at the outset “Dositheus the Samaritan,” but only to say that the author proposes to keep silence concerning both him and the Jews, and “to turn to those who have wished to make heresy from the Gospel,” the very first of whom, he says, is Simon Magus.[41] As for refutations, the tractate contains nothing resembling one, which has forced the supporters of the theory to assume that they were omitted for brevity’s sake. Nor does it in the least agree with our text in its description of the tenets and practices of heresies which the two documents treat of in common, such as Simon, Basilides, the Sethiani and others, and the differences are too great to be accounted for by supposing that the author of the later text was merely incorporating in it newer information.[42]